# Blocking system functions and graceful power off

**URL:** <https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553>\
**Category:** Firmware\
**Tags:** boron\
**Created:** [November 21, 2022, 2:46pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553 "2022-11-21T14:46:26Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![BenjaminAW](https://avatars.discourse-cdn.com/v4/letter/b/a698b9/32.png) [@BenjaminAW](https://community.particle.io/u/BenjaminAW)\
**Post date:** [November 21, 2022, 2:46pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/1 "2022-11-21T14:46:26Z")

</div>

Hi,

I’m writing firmware for a boron that is only allowed to stay powered for 15 minutes. This boron has to connect, then send messages, and then turn off the cellular modem gracefully ([TAN004](https://docs.particle.io/reference/technical-advisory-notices/tan004-power-off-recommendations-for-sara-r410m-equipped-devices/)) before turning off.

While reading the documentation, I found some functions that may block or prevent me from gracefully turning off the cellular in time.

- [Particle.connect()](https://docs.particle.io/reference/device-os/api/cloud-functions/particle-connect/): `After you call Particle.connect(), your loop will not be called again until the device finishes connecting to the Cloud. Typically, you can expect a delay of approximately one second.`  
**Does that mean that loop will not be called anymore if the device fails to connect?**

- [System functions](https://docs.particle.io/reference/device-os/api/system-thread/system-functions/): `Synchronous system functions always block the caller until the system has performed the requested operation. These are the synchronous system functions: [...] Particle.subscribe(), Particle.publish()`  
**Again, does it block in case of failure?**

- [Particle.timeSyncedLast()](https://docs.particle.io/reference/device-os/api/cloud-functions/particle-timesyncedlast/): `It is possible that the call will block for an indeterminate amount of time, possibly for as long as 10 minutes. This can occur if the system thread is busy trying to reconnect to cellular and is unable to do so. Doing operations that access the cellular modem or require access to the system thread (as is the case for Particle.timeSyncedLast()) from a separate worker thread is a good workaround.`  
**How come this function wasn’t in the list of the “synchronous system functions” above?**

So my plan right now is to make separate worker threads as advised above. However I’m concerned that it won’t allow me to gracefully turn off the cellular. For example: if one of my worker threads is blocked waiting for the system thread to finish reconnecting to cellular, then how can I be sure that Particle.disconnect() or Cellular.off() won’t also be blocked waiting for the system thread to finish its current operation?

Below is a simplified version of my code. **Let me know if you have any tips to make sure that the cellular turns off gracefully every time.** Boron is turned off automatically after 15 minutes no matter what.  
Thank you in advance.

```auto
SYSTEM_MODE(SEMI_AUTOMATIC);
SYSTEM_THREAD(ENABLED);

int state = 0;

void setup() {
}

void loop() {
    if (state == 0) {
        // Connect and sync time
        Particle.connect();
        waitFor(Particle.connected, 13*60*1000);
        if (Particle.connected()) {
            Particle.syncTime();
            waitFor(Particle.syncTimeDone, 10*1000);
            // Here I do use Particle.timeSyncedLast()
        }
        state = 1;
    }
    if (state == 1) {
        // Publish if necessary and there's enough time left
        if (millis() < 14*60*1000 && needsToSend()) {
            Particle.process();
            if (Particle.connected()) {
                Particle.publish(...);
            } else {
                state = 2;
            }
        } else {
            state = 2;
        }
    }
    if (state == 2) {
        // Disconnect gracefully
        Particle.disconnect(CloudDisconnectOptions().graceful(true).timeout(5000));
        waitFor(Particle.disconnected, 5000);
        Cellular.off();
        waitFor(Cellular.isOff, 30000);
        state = 3;
    }
}

```

---

<div class="post-metadata">

**Author:** ![rickkas7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/rickkas7/32/8681_2.png) [@rickkas7](https://community.particle.io/u/rickkas7)\
**Post date:** [November 21, 2022, 4:21pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/2 "2022-11-21T16:21:02Z")

</div>

The note for Particle.connect() only applies in non-threaded mode. It should not block in the threaded mode, which is why you need to call Particle.connected() to find out if it has connected. You don’t generally have to worry about connect blocking.

The list of synchronous functions is not complete. There are also two difference classes of blocking functions: those that do not return until the operation completes in non-threaded mode (that list) and functions that run on the system thread in threaded mode (timeSyncedLast). If the system thread is blocked, that will cause functions like timeSyncedLast to block.

Incidentally, you should not sync time after connecting to the cloud. It’s already done on every cloud connection so doing it again isn’t useful.

You can solve for almost every case with the following:

- Don’t sync time. Time.isValid() is safe to use.
- Do Particle.publish() and Cellular.RSSI() only from a worker thread
- Before publishing, also check for Particle.connected() and skip if not connected
- To see how to do the publish from a background thread see [this library](https://github.com/rickkas7/BackgroundPublishRK)
- Subscribe from setup() before connecting to the cloud; it won’t block in this case.

If you do these things you will mostly avoid the dreaded 10 minute blocking until the cellular modem resets situation.

---

<div class="post-metadata">

**Author:** ![BenjaminAW](https://avatars.discourse-cdn.com/v4/letter/b/a698b9/32.png) [@BenjaminAW](https://community.particle.io/u/BenjaminAW)\
**Post date:** [November 21, 2022, 4:50pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/3 "2022-11-21T16:50:10Z")

</div>

Thanks a lot! I’ll follow these guidelines. The reason I’m syncing time again is because I need time to be a little more accurate than up to the second.

And just to be sure, what will happen if for example my worker thread #1 calls Particle.publish(), it blocks because of bad cellular, then some seconds later my worker thread #2 calls Particle.disconnect() followed by Cellular.off() ?

I’m worried that my worker thread #2 won’t turn off the cellular as fast as I’d like it to if the system thread is blocked for whatever reason.

---

<div class="post-metadata">

**Author:** ![rickkas7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/rickkas7/32/8681_2.png) [@rickkas7](https://community.particle.io/u/rickkas7)\
**Post date:** [November 21, 2022, 4:56pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/4 "2022-11-21T16:56:22Z")

</div>

The RTC on the Boron only has one second resolution, and even then it's not particularly stable. It's really just a counter that's clocked off the MCU 32 kHz crystal oscillator which is not a precise time reference. Also the Particle cloud time sync does not take into account network latency, so it will always be slightly off. If you need really accurate time you should use GNSS (GPS) or an external high-accuracy RTC and NTP.

> And just to be sure, what will happen if for example my worker thread #1 calls Particle.publish(), it blocks because of bad cellular, then some seconds later my worker thread #2 calls Particle.disconnect() followed by Cellular.off() ?

If you check for Particle.connected() before the publish, it could block, but should only block for a maximum of 20 seconds.

---

<div class="post-metadata">

**Author:** ![BenjaminAW](https://avatars.discourse-cdn.com/v4/letter/b/a698b9/32.png) [@BenjaminAW](https://community.particle.io/u/BenjaminAW)\
**Post date:** [December 1, 2022, 8:44pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/5 "2022-12-01T20:44:00Z")

</div>

Hi again,

I investigated more and found issues with Cellular.off().

I use a simple code to check how long it takes to turn off the modem:

```auto
SYSTEM_MODE(SEMI_AUTOMATIC);
SYSTEM_THREAD(ENABLED);

SerialLogHandler logHandler(LOG_LEVEL_ALL);

uint8_t state = 0;
uint32_t disconnectMillis;

void setup() {
    delay(1000);
}

void loop() {
    if (state == 0) {
        Log.info("Particle.connect()");
        Particle.connect();
        disconnectMillis = 5000 + random(60000);
        state = 2;
    }
    
    if (state == 2 && millis() >= disconnectMillis) {
        Log.info("Particle.disconnect()");
        Particle.disconnect(CloudDisconnectOptions().graceful(true).timeout(5000));
        waitFor(Particle.disconnected, 5000);
        Log.info("Cellular.off()");
        Cellular.off();
        waitFor(Cellular.isOff, 180000);
        Log.info("Cellular.isOff() = %u", Cellular.isOff());
        state = 3;
    }
    
}

```

My boron is powered with a good battery and plugged via usb so I can read logs. We also decreased significantly the signal’s quality. After the modem is turned off, I turn the boron off, then try again. In case you’re wondering, I delay the disconnection by a random amount in case the issue is time sensitive.

**5% of the time it takes more than 20 seconds to turn off the modem.**  
**1% of the time it takes more than 50 seconds to turn off the modem.**

We’ve been having major issues with our modems dying randomly, this abnormal delay might explain why. It seems that `waitFor(Cellular.isOff, 30000);` as advised on TAN004 isn’t sufficient.

Here are the logs obtained from the code above:

> **64 seconds to turn off the modem (60038 ms → 124770 ms)**
>
> ```auto
> 0000001399 [app] INFO: Particle.connect()
> 0000001402 [system.nm] INFO: State changed: DISABLED -> IFACE_DOWN
> 0000001403 [system.nm] INFO: State changed: IFACE_DOWN -> IFACE_REQUEST_UP
> 0000001404 [ncp.client] TRACE: Powering modem on, ncpId: 0x44
> 0000001404 [net.pppncp] TRACE: NCP event 3
> 0000001405 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_POWERING_UP
> 0000001405 [system.nm] INFO: State changed: IFACE_REQUEST_UP -> IFACE_UP
> 0000001406 [system.nm] TRACE: Interface 4 power state changed: 4
> 0000001555 [net.pppncp] TRACE: NCP event 3
> 0000001556 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_UP
> 0000001556 [system.nm] TRACE: Interface 4 power state changed: 2
> 0000001556 [ncp.client] TRACE: Modem powered on
> 0000001557 [ncp.client] TRACE: Setting UART voltage translator state 1
> 0000001656 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000001756 [ncp.client] TRACE: Setting UART voltage translator state 1
> 0000002757 [ncp.at] TRACE: > AT
> 0000003758 [ncp.at] TRACE: > AT
> 0000004759 [ncp.at] TRACE: > AT
> 0000005760 [ncp.at] TRACE: > AT
> 0000006761 [ncp.at] TRACE: > AT
> 0000007269 [ncp.at] TRACE: < OK
> 0000007270 [ncp.client] TRACE: NCP ready to accept AT commands
> 0000007270 [ncp.at] TRACE: > AT
> 0000007271 [ncp.at] TRACE: < OK
> 0000007271 [ncp.at] TRACE: > ATI9
> 0000007273 [ncp.at] TRACE: < L0.0.00.00.05.12,A.02.19
> 0000007273 [ncp.at] TRACE: < OK
> 0000007274 [ncp.client] TRACE: App firmware: 219
> 0000007274 [ncp.at] TRACE: > AT+UGPIOC?
> 0000007275 [ncp.at] TRACE: < +UGPIOC:
> 0000007276 [ncp.at] TRACE: < 7,255
> 0000007276 [ncp.at] TRACE: < 16,255
> 0000007276 [ncp.at] TRACE: < 19,255
> 0000007277 [ncp.at] TRACE: < 23,0
> 0000007277 [ncp.at] TRACE: < 24,255
> 0000007277 [ncp.at] TRACE: < 25,255
> 0000007278 [ncp.at] TRACE: < 42,255
> 0000007278 [ncp.at] TRACE: < OK
> 0000007278 [ncp.at] TRACE: > AT+UGPIOR=23
> 0000007283 [ncp.at] TRACE: < +UGPIOR: 23,1
> 0000007283 [ncp.at] TRACE: < OK
> 0000007283 [ncp.client] INFO: Using internal SIM card
> 0000007284 [ncp.at] TRACE: > AT+CPIN?
> 0000007286 [ncp.at] TRACE: < +CME ERROR: SIM not inserted
> 0000008286 [ncp.at] TRACE: > AT+CPIN?
> 0000008287 [ncp.at] TRACE: < +PACSP0
> 0000008290 [ncp.at] TRACE: < +CPIN: READY
> 0000008290 [ncp.at] TRACE: < OK
> 0000008290 [ncp.at] TRACE: > AT+CCID
> 0000008294 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000008294 [ncp.at] TRACE: < OK
> 0000008295 [ncp.at] TRACE: > AT+IFC?
> 0000008297 [ncp.at] TRACE: < +IFC: 2,2
> 0000008297 [ncp.at] TRACE: < OK
> 0000008297 [ncp.at] TRACE: > AT+CFUN=0,0
> 0000008397 [ncp.at] TRACE: < OK
> 0000008397 [ncp.at] TRACE: > AT+CFUN=1,0
> 0000008401 [ncp.at] TRACE: < OK
> 0000008401 [ncp.at] TRACE: > AT+CPIN?
> 0000008403 [ncp.at] TRACE: < +CPIN: READY
> 0000008404 [ncp.at] TRACE: < OK
> 0000008404 [ncp.at] TRACE: > AT+CCID
> 0000008407 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000008407 [ncp.at] TRACE: < OK
> 0000008407 [ncp.at] TRACE: > AT+IFC?
> 0000008409 [ncp.at] TRACE: < +IFC: 2,2
> 0000008409 [ncp.at] TRACE: < OK
> 0000008410 [ncp.at] TRACE: > AT+IFC=2,2
> 0000008412 [ncp.at] TRACE: < OK
> 0000008413 [ncp.at] TRACE: > AT
> 0000008414 [ncp.at] TRACE: < OK
> 0000008414 [ncp.at] TRACE: > AT+IPR=460800
> 0000008424 [ncp.at] TRACE: < OK
> 0000009424 [ncp.at] TRACE: > AT
> 0000009427 [ncp.at] TRACE: < OK
> 0000009427 [ncp.at] TRACE: > AT+CCID
> 0000009430 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000009431 [ncp.at] TRACE: < OK
> 0000009431 [ncp.at] TRACE: > AT+CIMI
> 0000009433 [ncp.at] TRACE: < 310410352593854
> 0000009434 [ncp.at] TRACE: < OK
> 0000009434 [ncp.at] TRACE: > AT+UMNOPROF?
> 0000009438 [ncp.at] TRACE: < +UMNOPROF: 2
> 0000009439 [ncp.at] TRACE: < OK
> 0000009439 [ncp.at] TRACE: > AT+COPS=3,2
> 0000009442 [ncp.at] TRACE: < OK
> 0000009442 [ncp.at] TRACE: > AT+CGEREP=1,0
> 0000009444 [ncp.at] TRACE: < OK
> 0000009445 [ncp.at] TRACE: > AT+URAT?
> 0000009447 [ncp.at] TRACE: < +CME ERROR: Operation not supported
> 0000009448 [ncp.at] TRACE: > AT+CPSMS?
> 0000009452 [ncp.at] TRACE: < +CPSMS:0,,,"01100000","00000000"
> 0000009453 [ncp.at] TRACE: < OK
> 0000009453 [ncp.at] TRACE: > AT+CEDRXS?
> 0000009455 [ncp.at] TRACE: < +CEDRXS:
> 0000009455 [ncp.at] TRACE: < OK
> 0000009456 [ncp.at] TRACE: > AT+CMUX=0,0,,1509,,,,,
> 0000009460 [ncp.at] TRACE: < OK
> 0000009460 [mux] INFO: Starting GSM07.10 muxer
> 0000009461 [mux] INFO: Openning mux channel 0
> 0000009461 [mux] INFO: GSM07.10 muxer thread started
> 0000009465 [mux] INFO: Openning mux channel 1
> 0000009467 [ncp.at] TRACE: > AT
> 0000009472 [ncp.at] TRACE: < OK
> 0000009472 [ncp.client] TRACE: NCP state changed: 1
> 0000009473 [net.pppncp] TRACE: NCP event 1
> 0000009473 [net.ppp.client] TRACE: PPP thread event ADM_UP data=0
> 0000009474 [net.ppp.client] TRACE: State NONE -> READY
> 0000009477 [ncp.at] TRACE: > AT
> 0000009482 [ncp.at] TRACE: < OK
> 0000009483 [ncp.at] TRACE: > AT+CFUN?
> 0000009486 [ncp.at] TRACE: < +CFUN: 1
> 0000009486 [ncp.at] TRACE: < OK
> 0000009487 [ncp.at] TRACE: > AT+CCID
> 0000009492 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000009492 [ncp.at] TRACE: < OK
> 0000009493 [ncp.at] TRACE: > AT+CIMI
> 0000009498 [ncp.at] TRACE: < 310410352593854
> 0000009498 [ncp.at] TRACE: < OK
> 0000009499 [ncp.at] TRACE: > AT+CGDCONT?
> 0000009509 [ncp.at] TRACE: < +CGDCONT: 1,"IP","10569.mcs","0.0.0.0",0,0,0,0,0,0
> 0000009509 [ncp.at] TRACE: < +CGDCONT: 2,"IPV4V6","attm2mglobal","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0,0,0
> 0000009510 [ncp.at] TRACE: < OK
> 0000009510 [ncp.at] TRACE: > AT+CFUN?
> 0000009515 [ncp.at] TRACE: < +CFUN: 1
> 0000009516 [ncp.at] TRACE: < OK
> 0000009516 [ncp.at] TRACE: > AT+CEREG=2
> 0000009521 [ncp.at] TRACE: < OK
> 0000009521 [ncp.client] TRACE: NCP connection state changed: 1
> 0000009521 [net.pppncp] TRACE: NCP event 2
> 0000009522 [net.pppncp] TRACE: State changed event: 1
> 0000009522 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000009523 [ncp.at] TRACE: > AT+COPS?
> 0000009527 [ncp.at] TRACE: < +COPS: 0
> 0000009528 [ncp.at] TRACE: < OK
> 0000009528 [ncp.at] TRACE: > AT+CEREG?
> 0000009533 [ncp.at] TRACE: < +CEREG: 2,0
> 0000009534 [ncp.at] TRACE: < OK
> 0000024634 [ncp.at] TRACE: > AT+CEREG?
> 0000024641 [ncp.at] TRACE: < +CEREG: 2,1,"41C","104DF23",7
> 0000024643 [ncp.at] TRACE: < OK
> 0000024644 [ncp.at] TRACE: > AT+UCGED=5
> 0000024644 [ncp.at] TRACE: < +CEREG: 2
> 0000024644 [ncp.at] TRACE: < +CEREG: 1,"41C","104DF23",7
> 0000024649 [ncp.at] TRACE: < OK
> 0000024649 [ncp.at] TRACE: > AT+UCGED?
> 0000024655 [ncp.at] TRACE: < +RSRP: 355,700,"-134.50",
> 0000024655 [ncp.at] TRACE: < +RSRQ: 355,700,"-20.00",
> 0000024656 [ncp.at] TRACE: < OK
> 0000024755 [ncp.client] TRACE: NCP connection state changed: 2
> 0000024756 [mux] INFO: Openning mux channel 2
> 0000025922 [net.pppncp] TRACE: NCP event 100
> 0000025922 [net.pppncp] TRACE: New auth info
> 0000025925 [net.pppncp] TRACE: NCP event 2
> 0000025925 [net.pppncp] TRACE: State changed event: 2
> 0000025926 [ncp.at] TRACE: > AT+CIMI
> 0000025926 [net.ppp.client] TRACE: PPP thread event LOWER_UP data=0
> 0000025927 [net.ppp.client] TRACE: State READY -> CONNECT
> 0000025927 [net.ppp.client] TRACE: State CONNECT -> CONNECTING
> 0000025931 [ncp.at] TRACE: < 310410352593854
> 0000025932 [ncp.at] TRACE: < OK
> 0000025932 [ncp.at] TRACE: > AT
> 0000025936 [ncp.at] TRACE: < OK
> 0000025937 [ncp.at] TRACE: > AT+CGATT?
> 0000025945 [ncp.at] TRACE: < +CGATT: 1
> 0000025945 [ncp.at] TRACE: < OK
> 0000026946 [ncp.at] TRACE: > AT
> 0000026953 [ncp.at] TRACE: < OK
> 0000026954 [ncp.at] TRACE: > ATD*99***1#
> 0000026965 [ncp.at] TRACE: < CONNECT 150000000
> 0000026966 [net.ppp.client] TRACE: PPP phase -> Initialize
> 0000026966 [net.ppp.client] TRACE: PPP phase -> Establish
> 0000026967 [lwip.ppp] TRACE: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x58525ccc> <pcomp> <accomp>]
> 0000027120 [lwip.ppp] TRACE: rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xe33d823> <pcomp> <accomp>]
> 0000027121 [lwip.ppp] TRACE: sent [LCP ConfAck id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xe33d823> <pcomp> <accomp>]
> 0000027124 [lwip.ppp] TRACE: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x58525ccc> <pcomp> <accomp>]
> 0000027125 [lwip.ppp] TRACE: sent [LCP EchoReq id=0x0 magic=0x58525ccc]
> 0000027125 [net.ppp.client] TRACE: PPP phase -> Authenticate
> 0000027273 [lwip.ppp] TRACE: rcvd [LCP DiscReq id=0x1 magic=0xe33d823]
> 0000027276 [lwip.ppp] TRACE: rcvd [CHAP Challenge id=0x1 <0556600eed281016850bb271e9c8ea53>, name = "UMTS_CHAP_SRVR"]
> 0000027277 [lwip.ppp] TRACE: sent [CHAP Response id=0x1 <5cf2783c44205004308ce08e4a598173>, name = ""]
> 0000027279 [lwip.ppp] TRACE: rcvd [LCP EchoRep id=0x0 magic=0xe33d823 58 52 5c cc]
> 0000027427 [lwip.ppp] TRACE: rcvd [CHAP Success id=0x1 ""]
> 0000027427 [net.ppp.client] TRACE: PPP phase -> Network
> 0000027427 [lwip.ppp] TRACE: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <msdns1 8.8.8.8> <msdns2 8.8.4.4>]
> 0000027579 [lwip.ppp] TRACE: rcvd [IPCP ConfReq id=0x0]
> 0000027580 [lwip.ppp] TRACE: sent [IPCP ConfAck id=0x0]
> 0000027582 [lwip.ppp] TRACE: rcvd [IPCP ConfNak id=0x1 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027583 [lwip.ppp] TRACE: sent [IPCP ConfReq id=0x2 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027730 [lwip.ppp] TRACE: rcvd [IPCP ConfAck id=0x2 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027731 [system.nm] INFO: State changed: IFACE_UP -> IFACE_LINK_UP
> 0000027732 [net.ppp.client] TRACE: PPP thread event UP data=0
> 0000027733 [net.ppp.client] TRACE: State CONNECTING -> CONNECTED
> 0000027733 [net.pppncp] TRACE: Negotiated MTU: 1500
> 0000027733 [system.nm] INFO: State changed: IFACE_LINK_UP -> IP_CONFIGURED
> 0000027734 [net.ppp.client] TRACE: PPP phase -> Running
> 0000027735 [system] INFO: Cloud: connecting
> 0000027739 [system] WARN: Failed to load session data from persistent storage
> 0000040192 [system] ERROR: Failed to determine server address
> 0000040193 [system] WARN: Cloud socket connection failed: -230
> 0000048237 [system] WARN: Internet available, cloud not reachable
> 0000048237 [system] WARN: Handling cloud error: 3
> 0000048338 [system] INFO: Cloud: connecting
> 0000048341 [system] WARN: Failed to load session data from persistent storage
> 0000054293 [system] INFO: Cloud socket connected
> 0000054294 [comm.protocol.handshake] INFO: Establish secure connection
> 0000054299 [comm.dtls] INFO: (CMPL,RENEG,NO_SESS,ERR) restoreStatus=2
> 0000060038 [app] INFO: Particle.disconnect()
> 0000060038 [app] INFO: Cellular.off()
> 0000123144 [comm.dtls] ERROR: handshake failed -6800
> 0000123144 [comm.dtls] ERROR: Invalid handshake state
> 0000123148 [comm.protocol.handshake] ERROR: Handshake failed: 17
> 0000124349 [system] WARN: Internet available, cloud not reachable
> 0000124350 [system] WARN: Cloud handshake failed, code=-220
> 0000124601 [system] INFO: Cloud: disconnecting
> 0000124605 [system] INFO: Cloud: disconnected
> 0000124606 [ncp.at] TRACE: > AT+CFUN=0,0
> 0000124606 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000124607 [net.ppp.client] TRACE: State CONNECTED -> DISCONNECT
> 0000124607 [net.ppp.client] TRACE: State DISCONNECT -> DISCONNECTING
> 0000124608 [system.nm] INFO: State changed: IP_CONFIGURED -> IFACE_UP
> 0000124609 [net.ppp.client] TRACE: PPP phase -> Network
> 0000124609 [net.ppp.client] TRACE: PPP phase -> Establish
> 0000124609 [net.ppp.client] TRACE: PPP phase -> Disconnect
> 0000124610 [net.ppp.client] TRACE: PPP phase -> Dead
> 0000124611 [net.ppp.client] TRACE: PPP thread event ADM_DOWN data=0
> 0000124612 [net.ppp.client] TRACE: PPP thread event ERROR data=5
> 0000124613 [net.pppncp] ERROR: PPP error event data=5
> 0000124614 [net.ppp.client] TRACE: PPP thread event DOWN data=0
> 0000124615 [net.ppp.client] TRACE: State DISCONNECTING -> DISCONNECTED
> 0000124616 [net.ppp.client] TRACE: State DISCONNECTED -> NONE
> 0000124618 [system.nm] INFO: State changed: IFACE_UP -> IFACE_REQUEST_DOWN
> 0000124619 [system.nm] INFO: State changed: IFACE_REQUEST_DOWN -> IFACE_DOWN
> 0000124620 [system.nm] TRACE: Request to power off the interface
> 0000124621 [system.nm] TRACE: Interface 4 power state: 2
> 0000124623 [system.nm] INFO: State changed: IFACE_DOWN -> DISABLED
> 0000124711 [ncp.at] TRACE: < OK
> 0000124711 [ncp.client] TRACE: NCP connection state changed: 0
> 0000124711 [net.pppncp] TRACE: NCP event 2
> 0000124712 [net.pppncp] TRACE: State changed event: 0
> 0000124712 [net.pppncp] TRACE: NCP event 3
> 0000124712 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_POWERING_DOWN
> 0000124713 [system.nm] TRACE: Interface 4 power state changed: 3
> 0000124714 [ncp.client] TRACE: Try powering modem off using AT command
> 0000124712 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000124715 [ncp.at] TRACE: > AT+CPWROFF
> 0000124716 [ncp.at] TRACE: < +CEREG: 0
> 0000124719 [ncp.at] TRACE: < OK
> 0000124719 [ncp.client] TRACE: Waiting the modem to be turned off...
> 0000124754 [net.pppncp] TRACE: NCP event 3
> 0000124755 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_DOWN
> 0000124755 [system.nm] TRACE: Interface 4 power state changed: 1
> 0000124755 [ncp.client] TRACE: It takes 36 ms to power off the modem.
> 0000124756 [mux] INFO: Stopping GSM07.10 muxer
> 0000124756 [mux] INFO: Gracefully stopping GSM07.10 muxer
> 0000124756 [mux] INFO: Closing all muxed channels
> 0000124757 [mux] INFO: Closing mux channel 1
> 0000124758 [mux] INFO: Closing mux channel 2
> 0000124758 [mux] INFO: Muxed channel 3 already closed
> 0000124759 [mux] INFO: Muxed channel 4 already closed
> 0000124760 [mux] INFO: GSM07.10 muxer thread exiting
> 0000124761 [mux] INFO: GSM07.10 muxer stopped
> 0000124762 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000124763 [ncp.client] TRACE: Soft power off modem successfully
> 0000124764 [ncp.client] TRACE: Deinit modem serial.
> 0000124765 [ncp.client] TRACE: Modem already off
> 0000124765 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000124767 [ncp.client] TRACE: Soft power off modem successfully
> 0000124768 [ncp.client] TRACE: Deinit modem serial.
> 0000124768 [ncp.client] TRACE: NCP state changed: 0
> 0000124769 [net.pppncp] TRACE: NCP event 1
> 0000124770 [app] INFO: Cellular.isOff() = 1
> 
> ```

> **57 seconds to turn off the modem (62520 ms → 119966 ms)**
>
> ```auto
> 0000001404 [app] INFO: Particle.connect()
> 0000001507 [system.nm] INFO: State changed: DISABLED -> IFACE_DOWN
> 0000001509 [system.nm] INFO: State changed: IFACE_DOWN -> IFACE_REQUEST_UP
> 0000001509 [ncp.client] TRACE: Powering modem on, ncpId: 0x44
> 0000001509 [net.pppncp] TRACE: NCP event 3
> 0000001510 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_POWERING_UP
> 0000001510 [system.nm] INFO: State changed: IFACE_REQUEST_UP -> IFACE_UP
> 0000001511 [system.nm] TRACE: Interface 4 power state changed: 4
> 0000001660 [net.pppncp] TRACE: NCP event 3
> 0000001661 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_UP
> 0000001661 [system.nm] TRACE: Interface 4 power state changed: 2
> 0000001661 [ncp.client] TRACE: Modem powered on
> 0000001662 [ncp.client] TRACE: Setting UART voltage translator state 1
> 0000001761 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000001861 [ncp.client] TRACE: Setting UART voltage translator state 1
> 0000002863 [ncp.at] TRACE: > AT
> 0000003864 [ncp.at] TRACE: > AT
> 0000004865 [ncp.at] TRACE: > AT
> 0000005866 [ncp.at] TRACE: > AT
> 0000006867 [ncp.at] TRACE: > AT
> 0000007411 [ncp.at] TRACE: < OK
> 0000007411 [ncp.client] TRACE: NCP ready to accept AT commands
> 0000007411 [ncp.at] TRACE: > AT
> 0000007413 [ncp.at] TRACE: < OK
> 0000007413 [ncp.at] TRACE: > ATI9
> 0000007413 [ncp.at] TRACE: < AT
> 0000007413 [ncp.at] TRACE: < OK
> 0000007414 [ncp.at] TRACE: < L0.0.00.00.05.12,
> 0000007415 [ncp.at] TRACE: > AT+UGPIOC?
> 0000007415 [ncp.at] TRACE: < OK
> 0000007417 [ncp.at] TRACE: < +UGPIOC:
> 0000007417 [ncp.at] TRACE: < 7,255
> 0000007417 [ncp.at] TRACE: < 16,255
> 0000007418 [ncp.at] TRACE: < 19,255
> 0000007418 [ncp.at] TRACE: < 23,0
> 0000007418 [ncp.at] TRACE: < 24,255
> 0000007419 [ncp.at] TRACE: < 25,255
> 0000007419 [ncp.at] TRACE: < 42,255
> 0000007419 [ncp.at] TRACE: < OK
> 0000007420 [ncp.at] TRACE: > AT+UGPIOR=23
> 0000007422 [ncp.at] TRACE: < +UGPIOR: 23,1
> 0000007423 [ncp.at] TRACE: < OK
> 0000007423 [ncp.client] INFO: Using internal SIM card
> 0000007423 [ncp.at] TRACE: > AT+CPIN?
> 0000007426 [ncp.at] TRACE: < +CME ERROR: SIM not inserted
> 0000008425 [ncp.at] TRACE: > AT+CPIN?
> 0000008426 [ncp.at] TRACE: < +PACSP0
> 0000008429 [ncp.at] TRACE: < +CPIN: READY
> 0000008429 [ncp.at] TRACE: < OK
> 0000008430 [ncp.at] TRACE: > AT+CCID
> 0000008433 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000008434 [ncp.at] TRACE: < OK
> 0000008434 [ncp.at] TRACE: > AT+IFC?
> 0000008436 [ncp.at] TRACE: < +IFC: 2,2
> 0000008436 [ncp.at] TRACE: < OK
> 0000008437 [ncp.at] TRACE: > AT+CFUN=0,0
> 0000008475 [ncp.at] TRACE: < OK
> 0000008475 [ncp.at] TRACE: > AT+CFUN=1,0
> 0000008478 [ncp.at] TRACE: < OK
> 0000008478 [ncp.at] TRACE: > AT+CPIN?
> 0000008480 [ncp.at] TRACE: < +CPIN: READY
> 0000008480 [ncp.at] TRACE: < OK
> 0000008481 [ncp.at] TRACE: > AT+CCID
> 0000008484 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000008485 [ncp.at] TRACE: < OK
> 0000008485 [ncp.at] TRACE: > AT+IFC?
> 0000008487 [ncp.at] TRACE: < +IFC: 2,2
> 0000008487 [ncp.at] TRACE: < OK
> 0000008487 [ncp.at] TRACE: > AT+IFC=2,2
> 0000008489 [ncp.at] TRACE: < OK
> 0000008490 [ncp.at] TRACE: > AT
> 0000008491 [ncp.at] TRACE: < OK
> 0000008491 [ncp.at] TRACE: > AT+IPR=460800
> 0000008500 [ncp.at] TRACE: < OK
> 0000009501 [ncp.at] TRACE: > AT
> 0000009504 [ncp.at] TRACE: < OK
> 0000009504 [ncp.at] TRACE: > AT+CCID
> 0000009507 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000009508 [ncp.at] TRACE: < OK
> 0000009508 [ncp.at] TRACE: > AT+CIMI
> 0000009511 [ncp.at] TRACE: < 310410352593854
> 0000009511 [ncp.at] TRACE: < OK
> 0000009512 [ncp.at] TRACE: > AT+UMNOPROF?
> 0000009516 [ncp.at] TRACE: < +UMNOPROF: 2
> 0000009517 [ncp.at] TRACE: < OK
> 0000009517 [ncp.at] TRACE: > AT+COPS=3,2
> 0000009520 [ncp.at] TRACE: < OK
> 0000009520 [ncp.at] TRACE: > AT+CGEREP=1,0
> 0000009522 [ncp.at] TRACE: < OK
> 0000009523 [ncp.at] TRACE: > AT+URAT?
> 0000009525 [ncp.at] TRACE: < +CME ERROR: Operation not supported
> 0000009526 [ncp.at] TRACE: > AT+CPSMS?
> 0000009530 [ncp.at] TRACE: < +CPSMS:0,,,"01100000","00000000"
> 0000009531 [ncp.at] TRACE: < OK
> 0000009531 [ncp.at] TRACE: > AT+CEDRXS?
> 0000009533 [ncp.at] TRACE: < +CEDRXS:
> 0000009533 [ncp.at] TRACE: < OK
> 0000009534 [ncp.at] TRACE: > AT+CMUX=0,0,,1509,,,,,
> 0000009539 [ncp.at] TRACE: < OK
> 0000009539 [mux] INFO: Starting GSM07.10 muxer
> 0000009540 [mux] INFO: Openning mux channel 0
> 0000009540 [mux] INFO: GSM07.10 muxer thread started
> 0000009543 [mux] INFO: Openning mux channel 1
> 0000009546 [ncp.at] TRACE: > AT
> 0000009551 [ncp.at] TRACE: < OK
> 0000009551 [ncp.client] TRACE: NCP state changed: 1
> 0000009551 [net.pppncp] TRACE: NCP event 1
> 0000009552 [net.ppp.client] TRACE: PPP thread event ADM_UP data=0
> 0000009553 [net.ppp.client] TRACE: State NONE -> READY
> 0000009556 [ncp.at] TRACE: > AT
> 0000009560 [ncp.at] TRACE: < OK
> 0000009561 [ncp.at] TRACE: > AT+CFUN?
> 0000009565 [ncp.at] TRACE: < +CFUN: 1
> 0000009565 [ncp.at] TRACE: < OK
> 0000009566 [ncp.at] TRACE: > AT+CCID
> 0000009571 [ncp.at] TRACE: < +CCID: 89014103273525938548
> 0000009571 [ncp.at] TRACE: < OK
> 0000009572 [ncp.at] TRACE: > AT+CIMI
> 0000009576 [ncp.at] TRACE: < 310410352593854
> 0000009577 [ncp.at] TRACE: < OK
> 0000009577 [ncp.at] TRACE: > AT+CGDCONT?
> 0000009587 [ncp.at] TRACE: < +CGDCONT: 1,"IP","10569.mcs","0.0.0.0",0,0,0,0,0,0
> 0000009588 [ncp.at] TRACE: < +CGDCONT: 2,"IPV4V6","attm2mglobal","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0,0,0
> 0000009588 [ncp.at] TRACE: < OK
> 0000009589 [ncp.at] TRACE: > AT+CFUN?
> 0000009594 [ncp.at] TRACE: < +CFUN: 1
> 0000009594 [ncp.at] TRACE: < OK
> 0000009595 [ncp.at] TRACE: > AT+CEREG=2
> 0000009599 [ncp.at] TRACE: < OK
> 0000009600 [ncp.client] TRACE: NCP connection state changed: 1
> 0000009600 [net.pppncp] TRACE: NCP event 2
> 0000009600 [net.pppncp] TRACE: State changed event: 1
> 0000009601 [ncp.at] TRACE: > AT+COPS?
> 0000009601 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000009606 [ncp.at] TRACE: < +COPS: 0
> 0000009606 [ncp.at] TRACE: < OK
> 0000009607 [ncp.at] TRACE: > AT+CEREG?
> 0000009612 [ncp.at] TRACE: < +CEREG: 2,0
> 0000009612 [ncp.at] TRACE: < OK
> 0000024613 [ncp.at] TRACE: > AT+CEREG?
> 0000024623 [ncp.at] TRACE: < +CEREG: 2,1,"41C","104DF23",7
> 0000024623 [ncp.at] TRACE: < OK
> 0000024624 [ncp.at] TRACE: > AT+UCGED=5
> 0000024624 [ncp.at] TRACE: < +CEREG: 2
> 0000024625 [ncp.at] TRACE: < +CEREG: 1,"41C","104DF23",7
> 0000024634 [ncp.at] TRACE: < OK
> 0000024634 [ncp.at] TRACE: > AT+UCGED?
> 0000024640 [ncp.at] TRACE: < +RSRP: 355,700,"-135.20",
> 0000024640 [ncp.at] TRACE: < +RSRQ: 355,700,"-20.00",
> 0000024640 [ncp.at] TRACE: < OK
> 0000024740 [ncp.client] TRACE: NCP connection state changed: 2
> 0000024741 [mux] INFO: Openning mux channel 2
> 0000025907 [net.pppncp] TRACE: NCP event 100
> 0000025908 [net.pppncp] TRACE: New auth info
> 0000025910 [net.pppncp] TRACE: NCP event 2
> 0000025911 [net.pppncp] TRACE: State changed event: 2
> 0000025911 [net.ppp.client] TRACE: PPP thread event LOWER_UP data=0
> 0000025912 [net.ppp.client] TRACE: State READY -> CONNECT
> 0000025912 [net.ppp.client] TRACE: State CONNECT -> CONNECTING
> 0000025912 [ncp.at] TRACE: > AT+CIMI
> 0000025916 [ncp.at] TRACE: < 310410352593854
> 0000025917 [ncp.at] TRACE: < OK
> 0000025917 [ncp.at] TRACE: > AT
> 0000025925 [ncp.at] TRACE: < OK
> 0000025925 [ncp.at] TRACE: > AT+CGATT?
> 0000025933 [ncp.at] TRACE: < +CGATT: 1
> 0000025933 [ncp.at] TRACE: < OK
> 0000026935 [ncp.at] TRACE: > AT
> 0000026942 [ncp.at] TRACE: < OK
> 0000026943 [ncp.at] TRACE: > ATD*99***1#
> 0000026955 [ncp.at] TRACE: < CONNECT 150000000
> 0000026955 [net.ppp.client] TRACE: PPP phase -> Initialize
> 0000026956 [net.ppp.client] TRACE: PPP phase -> Establish
> 0000026956 [lwip.ppp] TRACE: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x58525cbc> <pcomp> <accomp>]
> 0000027109 [lwip.ppp] TRACE: rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xe6503fd> <pcomp> <accomp>]
> 0000027110 [lwip.ppp] TRACE: sent [LCP ConfAck id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xe6503fd> <pcomp> <accomp>]
> 0000027112 [lwip.ppp] TRACE: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x58525cbc> <pcomp> <accomp>]
> 0000027113 [lwip.ppp] TRACE: sent [LCP EchoReq id=0x0 magic=0x58525cbc]
> 0000027114 [net.ppp.client] TRACE: PPP phase -> Authenticate
> 0000027262 [lwip.ppp] TRACE: rcvd [LCP DiscReq id=0x1 magic=0xe6503fd]
> 0000027264 [lwip.ppp] TRACE: rcvd [CHAP Challenge id=0x1 <2d2d22ee1d140df96b28a73b1b96dcbc>, name = "UMTS_CHAP_SRVR"]
> 0000027266 [lwip.ppp] TRACE: sent [CHAP Response id=0x1 <79934e310d08df6e2eaae711efa913e1>, name = ""]
> 0000027267 [lwip.ppp] TRACE: rcvd [LCP EchoRep id=0x0 magic=0xe6503fd 58 52 5c bc]
> 0000027415 [lwip.ppp] TRACE: rcvd [CHAP Success id=0x1 ""]
> 0000027415 [net.ppp.client] TRACE: PPP phase -> Network
> 0000027416 [lwip.ppp] TRACE: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <msdns1 8.8.8.8> <msdns2 8.8.4.4>]
> 0000027569 [lwip.ppp] TRACE: rcvd [IPCP ConfReq id=0x0]
> 0000027569 [lwip.ppp] TRACE: sent [IPCP ConfAck id=0x0]
> 0000027571 [lwip.ppp] TRACE: rcvd [IPCP ConfNak id=0x1 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027572 [lwip.ppp] TRACE: sent [IPCP ConfReq id=0x2 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027719 [lwip.ppp] TRACE: rcvd [IPCP ConfAck id=0x2 <addr 10.210.205.248> <msdns1 174.47.40.106> <msdns2 174.47.20.106>]
> 0000027720 [system.nm] INFO: State changed: IFACE_UP -> IFACE_LINK_UP
> 0000027721 [net.ppp.client] TRACE: PPP thread event UP data=0
> 0000027722 [net.ppp.client] TRACE: State CONNECTING -> CONNECTED
> 0000027722 [net.pppncp] TRACE: Negotiated MTU: 1500
> 0000027722 [system.nm] INFO: State changed: IFACE_LINK_UP -> IP_CONFIGURED
> 0000027723 [net.ppp.client] TRACE: PPP phase -> Running
> 0000027724 [system] INFO: Cloud: connecting
> 0000027728 [system] WARN: Failed to load session data from persistent storage
> 0000043198 [system] ERROR: Failed to determine server address
> 0000043198 [system] WARN: Cloud socket connection failed: -230
> 0000051198 [system] WARN: Internet test failed: DNS
> 0000051198 [system] WARN: Handling cloud error: 2
> 0000051298 [system] INFO: Cloud: connecting
> 0000051300 [system] WARN: Failed to load session data from persistent storage
> 0000062520 [app] INFO: Particle.disconnect()
> 0000062520 [app] INFO: Cellular.off()
> 0000064837 [system] INFO: Cloud socket connected
> 0000064837 [comm.protocol.handshake] INFO: Establish secure connection
> 0000064843 [comm.dtls] INFO: (CMPL,RENEG,NO_SESS,ERR) restoreStatus=2
> 0000111786 [comm.dtls] ERROR: handshake failed -6800
> 0000111787 [comm.dtls] ERROR: Invalid handshake state
> 0000111791 [comm.protocol.handshake] ERROR: Handshake failed: 17
> 0000119198 [system] WARN: Internet test failed: DNS
> 0000119198 [system] WARN: Cloud handshake failed, code=-220
> 0000119448 [system] INFO: Cloud: disconnecting
> 0000119448 [system] INFO: Cloud: disconnected
> 0000119449 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000119450 [net.ppp.client] TRACE: State CONNECTED -> DISCONNECT
> 0000119450 [net.ppp.client] TRACE: State DISCONNECT -> DISCONNECTING
> 0000119450 [ncp.at] TRACE: > AT+CFUN=0,0
> 0000119451 [system.nm] INFO: State changed: IP_CONFIGURED -> IFACE_UP
> 0000119452 [net.ppp.client] TRACE: PPP phase -> Network
> 0000119452 [net.ppp.client] TRACE: PPP phase -> Establish
> 0000119452 [net.ppp.client] TRACE: PPP phase -> Disconnect
> 0000119453 [net.ppp.client] TRACE: PPP phase -> Dead
> 0000119453 [net.ppp.client] TRACE: PPP thread event ADM_DOWN data=0
> 0000119454 [net.ppp.client] TRACE: PPP thread event ERROR data=5
> 0000119455 [net.pppncp] ERROR: PPP error event data=5
> 0000119456 [net.ppp.client] TRACE: PPP thread event DOWN data=0
> 0000119457 [net.ppp.client] TRACE: State DISCONNECTING -> DISCONNECTED
> 0000119458 [net.ppp.client] TRACE: State DISCONNECTED -> NONE
> 0000119460 [system.nm] INFO: State changed: IFACE_UP -> IFACE_REQUEST_DOWN
> 0000119464 [system.nm] INFO: State changed: IFACE_REQUEST_DOWN -> IFACE_DOWN
> 0000119464 [system.nm] TRACE: Request to power off the interface
> 0000119464 [system.nm] TRACE: Interface 4 power state: 2
> 0000119465 [system.nm] INFO: State changed: IFACE_DOWN -> DISABLED
> 0000119907 [ncp.at] TRACE: < OK
> 0000119907 [ncp.client] TRACE: NCP connection state changed: 0
> 0000119907 [net.pppncp] TRACE: NCP event 2
> 0000119908 [net.pppncp] TRACE: State changed event: 0
> 0000119908 [net.pppncp] TRACE: NCP event 3
> 0000119908 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_POWERING_DOWN
> 0000119909 [system.nm] TRACE: Interface 4 power state changed: 3
> 0000119910 [ncp.client] TRACE: Try powering modem off using AT command
> 0000119908 [net.ppp.client] TRACE: PPP thread event LOWER_DOWN data=0
> 0000119911 [ncp.at] TRACE: > AT+CPWROFF
> 0000119911 [ncp.at] TRACE: < +CEREG: 0
> 0000119915 [ncp.at] TRACE: < OK
> 0000119915 [ncp.client] TRACE: Waiting the modem to be turned off...
> 0000119950 [net.pppncp] TRACE: NCP event 3
> 0000119951 [net.pppncp] TRACE: NCP power state changed: IF_POWER_STATE_DOWN
> 0000119951 [system.nm] TRACE: Interface 4 power state changed: 1
> 0000119952 [ncp.client] TRACE: It takes 37 ms to power off the modem.
> 0000119952 [mux] INFO: Stopping GSM07.10 muxer
> 0000119952 [mux] INFO: Gracefully stopping GSM07.10 muxer
> 0000119952 [mux] INFO: Closing all muxed channels
> 0000119953 [mux] INFO: Closing mux channel 1
> 0000119953 [mux] INFO: Closing mux channel 2
> 0000119954 [mux] INFO: Muxed channel 3 already closed
> 0000119955 [mux] INFO: Muxed channel 4 already closed
> 0000119955 [mux] INFO: GSM07.10 muxer thread exiting
> 0000119956 [mux] INFO: GSM07.10 muxer stopped
> 0000119957 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000119958 [ncp.client] TRACE: Soft power off modem successfully
> 0000119959 [ncp.client] TRACE: Deinit modem serial.
> 0000119960 [ncp.client] TRACE: Modem already off
> 0000119961 [ncp.client] TRACE: Setting UART voltage translator state 0
> 0000119962 [ncp.client] TRACE: Soft power off modem successfully
> 0000119963 [ncp.client] TRACE: Deinit modem serial.
> 0000119964 [ncp.client] TRACE: NCP state changed: 0
> 0000119964 [net.pppncp] TRACE: NCP event 1
> 0000119966 [app] INFO: Cellular.isOff() = 1
> 
> ```

I believe that for this issue, there is nothing I can do except increase the amount of time that we wait for the modem to turn off? How about calling `Cellular.command("AT+CPWROFF");` myself?

---

<div class="post-metadata">

**Author:** ![rickkas7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/rickkas7/32/8681_2.png) [@rickkas7](https://community.particle.io/u/rickkas7)\
**Post date:** [December 2, 2022, 9:47am UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/6 "2022-12-02T09:47:32Z")

</div>

In the two cases where it took a long time to turn off cellular, you disconnected from the cloud before it finished connecting. I’m not completely sure which will be the best method, but a few things that might work:

- Wait for connection to succeed or fail on its own is the best if you can.
- If not Particle.connected(), disconnect with graceful false. Not positive this will make a difference but it might.
- If not Particle.connected() jump directly to Cellular.off, not disconnecting from the cloud at all.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/particle/original/3X/6/4/64635adccc35238caa19e9b553ec3e98b163d026.png) [@system](https://community.particle.io/u/system)\
**Post date:** [June 2, 2023, 9:48pm UTC](https://community.particle.io/t/blocking-system-functions-and-graceful-power-off/63553/7 "2023-06-02T21:48:22Z")

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