Communication Issue Humidity and Temperature Transmitter

Troubleshooting
1

Hello all,

I am having an issue with the relative humidity and temperature transmitter (specifically HUM C - Temco Temp and RH Transmitter). I am using an RS485 to USB converter to connect this unit to a data logger (Congrego - Congrego Data Logger).

I am able to poll both of these values and the settings are correct for receiving the data, however less than 50% of the polls are receiving a value from the transmitter:

Modbus Polling Settings:

  • Baud Rate: 115200
  • Data Bits: 8
  • Parity: None
  • Stop Bits: 1
  • Handshake: None

Temperature Polling:

  • Register Polled: Holding Register
  • Register Address: 101

Relative Humidity Polling:

  • Register Polled: Holding Register
  • Register Address: 304

Any ideas what might be causing this issue? Potentially I am missing something very simple.

Either way, thank you for your help and your time,
. James

2

I believe there is a setting in the T3000 front end for adding a short delay on the modbus replies. The hum can reply too quickly and some polling devices need a little delay before the reply. check around in the t3000 software and it should show up. also you could try polling with a PC which can switch from poll （sending) to receive very fast, see if the issue persists.

Maurice

3

In T3000, select your device, then select Configuration and Advanced Parameters (gear icon), you will see a setting for Modbus Reply Delay; I believe the default setting is 5 mSec.

Regards, Steve

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