Hi @ericpietrowicz Thanks for responding.
All three of the yellow jumpers are enabled and on J2, J3, and J4. I have not removed any of them, the board is in its default configuration.
Reversing the RX and TX wires from the Photon to the Click 3v3 caused timeout errors. And in the serial monitor continued E2 errors.
Bus monitor:
[RTU]>Tx > 16:10:40:259 - 01 06 00 05 FF FF 98 7B
Sys > 16:10:40:775 - Error : Timeout
[RTU]>Tx > 16:10:41:258 - 01 06 00 05 FF FF 98 7B
Sys > 16:10:41:775 - Error : Timeout
[RTU]>Tx > 16:10:42:275 - 01 06 00 05 FF FF 98 7B
Sys > 16:10:42:777 - Error : Timeout
[RTU]>Tx > 16:10:42:979 - 01 03 00 05 00 01 94 0B
Sys > 16:10:43:491 - Error : Timeout
I have also been looking at this forum post with similar issues, but it has yet to be helpful to me.
Modbus Master library issue - Firmware / Libraries - Particle