step 5 refreshment on FB40

what is:
bg, p/q, knkt, ogr, ugr, einz, xa, fb, bu, tbit
???
I am troubleshooting an S5 with many FB40's and can't remember my German today.

Looks Like An Analog Scaling Block

http://cache.automation.siemens.com/dnl/jExMDU0MwAA_1091978_HB/6ES5%20998-0UB23.pdf

This is for a 100U processor, but the ins and outs look decidely the same..... this was a built in FB250 look at section 11.6

BG is slot number
KNKT is channel number
OGR is upper limit
UGR is lower limit
Einz - is single scan
XA is scaled value
FB is an error bit
BU is a range violation bit...

Tbit is busy signal - cpu is processing the scale block

what CPU is this program in????

I'd have to go look at the PLC rack to remember which CPU this one is. We've been upgrading everything to S7 or GE, so I've gotten a little out of touch. The link you sent is pure gold, though. I really appreciate it.

FB 40 could be a standard Analog function block or a roll your own

Normally Siemens number their blocks FB200 & up but you can re-name them to avoid conflicts with blocks of the same number.
If the block is a standard siemens then you will not be able to open it (unless you know how?),

Yeah, FB250 looks earily the same. They must have renamed it during commissioning many years ago. No, we can't open it, so I'm thinking there is a German engineer laughing himself to sleep at night, glad he could give us headaches.