Regarding problem in failsafe DO Module ET200M

Dear Team,

We are using ET200M remote IO's for failsafe signals. In this we are using Failsafe DO Module (MLFB NO: 6ES7326-2BF10-0AB0).

In this module we are getting "External P short circuit / Cross fault" message in diagnostic buffer of the module. Can anybody explain me that what exactly it is? What needs to be take care to remove this fault?

Cause of this message is as below:

We have sending 1 signal through this DO module and suddenly there is open circuit at the output. At this very moment this channel get passivated but it also passivated other active channel of the same modules.

Kindly help.

Hi,

Wireing... 

In the SIMATIC Automation System S7-300 ET 200M Distributed I/O Device Fail-safe signal modules manual page 189  you can read:

"If the  F-SM  detects  an external  P-short  circuit  on  a channel,  it  will  turn  off  all  channels  that route  "1"  signals  and  are  not  configured  redundantly. The channels  that  are  actually  affected will  be  determined  afterwards;  channels  without active fault  can be reintegrated  at  this  time.   "

Anyway same manual says on page 138:

"To prevent  short  circuits  between  the  P  and  M switches  of  a fail-safe digital  output,  you must  route the cables  used  to connect  the relays  on the P  and  M switches  in a cross-circuitproof  manner  (e.g.,  as  separate,  unsheathed cables  or  in separate cable  ducts). "

Wireing... Double check cause no harm!

MicroMan

Hi,

Wireing... 

In the SIMATIC Automation System S7-300 ET 200M Distributed I/O Device Fail-safe signal modules manual page 189  you can read:

"If the  F-SM  detects  an external  P-short  circuit  on  a channel,  it  will  turn  off  all  channels  that route  "1"  signals  and  are  not  configured  redundantly. The channels  that  are  actually  affected will  be  determined  afterwards;  channels  without active fault  can be reintegrated  at  this  time.   "

Wireing... Double check cause no harm!

Dear MicroMan,

Thanks for your help.

I read this statement in the manual before but I did not get the meaning of statement "External P-short circuit on a channel". Because what all I am doing with this channel is I am making it open circuit, so how it is showing this message?

Can you elaborate more? Can you tell me the meaning of this message?

Hi,

Check the recomended wireing schemes in the  SIMATIC Automation System S7-300 ET 200M Distributed I/O Device Fail-safe signal modules manual.

How the card detects the non continous loop? Read about this briefly in above manual page 354 "dark period"  and page 358 "light period". That is how your card detects the error.

System integrity... very important!

I hope I could  help!