Siemens Step 7 question

[johnnie]

What is significant about FB80 and why is important to load this block even though nothing is in it??

 

[The Dark Knight]

?FB80???

FB80 the lead/lag algorithm from the ti-s7 blocks

Do you mean OB80

OB80 is a scan cycle time fault

If your preset scan cycle time is exceeded and you don't have OB80 loaded, your CPU will STOP

 

[johnnie]

my bad..i did mean OB 80
Thanks for the reply!!

 

[PLucas]

Johnnie

These OB's are blank so that you may program them the way you want them. For instance, if OB80 is called by the PLC you might program a 'move' to 'pull' out the error code, then depending on what the error code is you could then either restart the PLC, put it into stop mode, bring up an alarm on a HMI etc.

These OB's are called by the PLC when it faults and if the OB is not there the PLC goes into stop mode. If you don't program these OB's then you will not know if the PLC is faulting, as it will call the OB, process it, even with nothing in it, and then carry on,

That's my understanding of these OB's, it might not be totally correct, perhaps someone could confirm this, maybe Jean Pierre could.

Paul