Hey everyone,
I’m currently working with a PT21A01 temperature acquisition module that’s hooked up via a RAK7431 for RS485-to-LoRaWAN conversion. The sensor exposes two registers that I’m interested in:
0x0000 for the temperature value
0x0020 for the PT100 resistance value
Both are read-only and non-contiguous. Naturally, I tried to combine these polling instructions into a single uplink using function code 03 (Read Holding Registers), but the sensor threw back an error (something like “Illegal Data Value”).
My questions are:
Is there any way to merge these two polling requests into a single uplink? Or am I just destined to send two separate requests every time?
Thanks in advance for your help!
Cheers,
Camila Gomez