CX5020 + EK1101 - few question

Hi everybody,

I`m starting with programing Beckhoff PLC. I have setup with: CX5020 + EL2008 + EL1004 with connected EK1101 + EL2008 + EL1104. PLC contain program where inputs from EK coupler are maped to the outputs in CX rack.
I have question about network diagnostic becasue in situation when input on EK coupler is high and communication is broken (disconnectd RJ cable whatever) output is still in high state.
I have bigger experience with Siemens PLC and there if communictation between PLC and remote I/O stytem will be loose then PLC clearing input image himself. How is it with Beckhoff? I can`t find any materials on beckhoff website.

Regards.
finch

Each EtherCAT output terminal channel has a watchdog state you can set for if communications is lost. In the "System" section of your Visual Studio project ("System Manager" program if TwinCAT 2), highlight the module and poke around in the settings (perhaps CoE tab). I haven't used the feature since we usually handle it differently via their older KL3692 Watchdog terminal.

Hi,

Thanks for Your reply.
I know about watchdog and I sow many diagnostic variables in TwinCat manager. I`m asking how protect PLC program in situation when slave is missing on the bus.
Now I have maping between PLC manager, and PLC contain program like this:
-|I0.0|---(Q0.0)
and this is working like it should, but if Q0.0 is high and I disconnect slave station from subnet Q0.0 is still energized.
I don`t know that I`m inccorect configured something in Tcat manager or I should map diagnostic bits to the PLC program and clear right outputs bits by myself.

Regards
finch

Sorry, I don't know what you mean by "protect PLC program".

If you break communication to a terminal, I think the PLC code variable will hold the last input value read. Output values are set by the PLC code, and it assumes the System makes them happen in the terminal. System Manager can poll output channels for their actual state. Perhaps one could do the same in PLC code (I haven't tried). More commonly, I expect people read status variables of the terminal and coupler to insure the communication is active. Also, look at the Redundancy option to assure communication. A higher-level check is to physically wire each output back to an input to assure that each output you try to set is actually realized, which is what we do for critical systems.

Someone else may answer who knows what is commonly done w/ Siemens PLC's and knows exactly what you are referring to.

"protect PLC program" mean protect machine/system against unstable situations caused missing information from inputs.

"If you break communication to a terminal, I think the PLC code variable will hold the last input value read." - It is exactly like You wrote.

"I expect people read status variables of the terminal and coupler to insure the communication is active." This is point of this thread. I trying to solve this question but previously I thought that I`m doing something bad in to system configuration and PLC holding input status before communication was broken.

Redundancy and safety is to already to high level for me
Now I`m working with remote I/O and Ethercat. Generally diagnostic is easier like in Siemens where You must calling dedicated functions and decode result for each module.

If your EtherCAT outputs don't go to their default state (non-energized) if the ESC's dont receive an update from the EtherCAT master, the solution is to enable the SM and PDI watchdogs in the ESC. This should however be enabled by default, but I'd be looking at these options for the EL2008 you have from your project:
https://infosys.beckhoff.com/italiano.php?content=../content/1040/el28xx/html/Bt_Ec_Watchdog.htm&id=