M172 CAN Expansion Bus

[Wahlo]

Hi, 

I have a setup with the TM172PDG42RI and two TM172E28R connected on the CAN expansion bus. I was wondering if there is a system variable on the controller to "restart" the CAN communication. What I am experiencing is that if I have the controller started up first before starting up the expansion modules, the controller would not communicate with the expansion module. The controller would need to be reboot to re-establish the communication. 

[Bastian_Schmitz · Accepted solution]

Hi , so far I knwo there is at the moment not a target variable to restart the CAN communication. During the bootup the PLC will send a start Signal to all  Slave devices in the network. If the Expansion starts later like you described it will not work. 

[FedericoM]

Hi,

this option is available on TM173O with target block:

sysCopm_Reboot(COPM_CHN_ENUM#COPM_CHN_CAN0)

On TM172 the only option is trigger a PLC reboot from background task:

IF xRebootController THEN

xRet:=sysWD_Background(0);

END_IF;