TM171 RS485 Malfunction

[Josh1]

Im using Modicon TM171O

Whenever I upload program to the PLC, After the power cycle it does not reconnect to the Ecostuxure HVAC software.

It shows the error "Can not connect to the target"

Im certain of the modbus parameters, im using plc address as 1, baudrate as 9600, parity as Even.

Can someone help? Thanks!

[KosmoDrome]

Hi, I have the same problem.  Have project with Fancoil Units - 4 pcs. at one place. Each of them have own TM171ODM22R and connects to BMS by modbus. Suddenly 3 of 4 units lost the 485 connection and impossible to connect throug the program cable and Ecostructure HVAC anymore.  CAN NOT CONNECT TO THE TARGET. 

Installed new ones TM171, ECOSTRUCTURE HVAC programm uploaded ok to the unit, after power cycle all was still good. But after I connected it to the system with other units, again lost connection and cant do it anymore. CAN ANYBODY HELP?

[Bastian_Schmitz]

TM171O has only 1 Serial Line. Internal the RS485 ressources are shared with the DMI ressources. A combind connection is not possible. If you need a combinde connection you need to add a TM171ALAN Modul. In that case you get a second serial line. Or you use TM173O instead. The new one has not longer such a problem.