I’m having trouble with RS485 communication on my T3-TB-11i. Has anyone else encountered a similar situation and found a solution?
I connected one Weintek HMI to three T3-TB-11i units (main RS485 port, Bacnet MSTP, baud rate 19200). One T3-TB-11i unit reads the values of two temperature & humidity sensors via the RS485 sub port (Modbus master, baud rate 9600). The devices are successfully connected and display the sensor values on the HMI. However, at times the T3-TB-11i unit cannot read the sensor values. Upon inspection, I found that the RS485 sub port automatically changed its baud rate to 115200.
When I connected an HMI to a T3-TB-11i (the same device) using Bacnet/IP, the T3-TB-11i read sensor values via the RS485 Sub port, Modbus master, baud rate 9600. The connection was very stable, without the problems I experienced initially.
Firmware 65.9
I recently updated to firmware 67.4, but it keeps restarting after about 20-30 minutes.
On the T3-TB-11i device:
I used the RS485 MAIN connects to Weintek HMI (MSTP, 19200, 8N1). RS485 SUB to read sensor values (Modbus master, 9600, 8N1). The input (IN1 → IN11) continuously recorded strange values. When I turned off the RS485 SUB port, the input value returned to 0. I selected 4-20mA and 0-10V inputs.
There’s another issue, the T3-TB-11i device frequently restarts itself when using both RS485 ports.
I checked with firmware versions rev67.9 and rev68.0 have this problem.
We acknowledge that there is currently a conflict when the RS485 MAIN port and RS485 SUB port are used simultaneously on the T3-TB-11i. When the RS485 SUB port is enabled, it may also cause abnormal readings on INPUT1–INPUT11.
Our engineer Chelsea is actively working on resolving both the dual RS485 port conflict and the input data abnormality in firmware.
There is another problem:
T3-TB-11i restarts automatically. Could noise suppression help improve?
I noticed that the RS485 interface provides three terminals: [ + ], [ - ], and [ “GND” ].
Could you advise on the correct way to connect the GND wire?
Should the shield of the STP AWG cable be connected to GND or PE (earth)?
What impact does not connecting GND have on RS485 communication reliability?
Restarting: This is not normal behaviour, you could try with a 24vac power supply. Tie the GND of the power supply to earth at each cabinet and each controller.
RS485: Connect A to A and B to B throughout the system and that will do fine for the majority of your projects, a GND is not even required between devices.
As the number of devices and power supplies increases then grounding becomes more important. Tie GND to earth at all power supplies and as much as feasible also the GND of the various controllers, also tie that to earth.
Shield: If you have a shield tie that to earth and/or GND on one side of the cable, leave the other end floating. (Only one end goes to ground, that’s right).
However, only the device using two RS485 ports simultaneously experienced restarts. I changed the timeout and response times on the HMI, and it improved the boot time from 2 hours to 10 hours (I recorded the maximum time for each setting).
This is a Network Health image:
Glad to see that diagnostics dialog is useful. We will set up a test and work to repeat the issues/ come up with a solution to extend the reboot times.
