HEllo again plc 5/20 cpt what am I missing

[Ron Beaufort]

on your IFE setup screen you have the Data Format set for BCD - that needs to be Two's Complement Binary for a PLC-5 system ... I haven't had time to check the rest of your system - and I won't have any spare time until MAYBE tomorrow evening ...

also - you should be aware that this type of module has jumpers inside it that must be properly set to configure the individual channels for "current" or for "voltage" - and for "single-ended" or "differential" wiring ... have you checked those jumpers? ...

in the meantime, change the Data Format and see if things start to fall into place ... there's a good chance that this is the biggest part of your problem ...

PS Edit ... I just noticed that you have some of the "Range" settings entered for 0 to 20 mA (etc.) - instead of for the 4 to 20 mA signals that you mentioned ... double-check those settings too ...

hope this helps ... signing off ...

.

 

[Gil47]

As i have the AI"s looped to a slc 5/04 card and the numbers are exact on them.
in the PLC 5 @ 4 ma raw counts = (2070-2085) never steady always bouncing

I read this as a 4 - 20 mA signal is being read by a 504 processor and the same 4 - 20 mA loop continues on to be read by a PLC 5/20.

If so are you using differential input or single ended on the PLC 5

I am suspecting common mode noise.

 

[controlconcepts]

1. yes Ron the you were right about the two's complementary. But something real odd is happening with that.

let me describe more of what the setup is for clarification.

slot zero... 12 bit analog 0-20 ma output
slot one......12 bit analog 4-20 ma output
slot two......12 bit analog 8 ch input
setup for 8 channels differential
.............................all jumpers set properly
ok I go into I?O configuration select two's complement binary.
I have the 4-20 ma output's 1-3 wired directly to inputs 1-3 on the 8 ch input card. input scaling on-board the card is 0 16533.
in both cards acctualy. So I source a max signal 16533 should be 20 ma. And it maxes out to 16533,the analog input great. now if i go into the I/O config screen and slect twos Comp. and Accept edits (with Two's comp. selected to be downloaded to the card) hit accept and the analog input instantly changes from 16533 to 4095... this seems to happen on all analog cards.

Ron also the reason some of the analog inputs were set to o-20ma was that I had been testing the other card in slot zero to see if there was a difference..
now if i go into any analog card and select ( just select Two's Comp) and DO NOT Accept edits the values go back to 0-16533 like the card's integer file is set to.

 

[sthompson]

0-4095 is the Default Range for the AB 1771-IFE Cards. The maximum Range for the Card is -9999 to +9999.

Stu....

 

[Ron Beaufort]

input scaling on-board the card is 0 16533.

I'm not sure what you mean by that statement ... the scaling should be 0 to 4095 ...

here's what I'm guessing: you're looking at the scaling values as they have been stored in the data table (for example: the values stored at N14:18, N14:20, etc.) ...

don't do that ...

when you look at those in the default radix of DECIMAL then yes, indeed the values will be 16533 ...

but ...

the analog input module will accept and read and interpret those numbers in the HEX/BCD radix – not in DECIMAL ...

so ...

what looks like a Raw/Max channel scaling value of 16533 to us humans, will be interpreted as a value of 4095 by the analog input module ...

secret handshake: quit looking at the values stored in the data file – and instead look at the values as they're shown on the module's setup screen (like the screen shots that I've posted above) ... the setup screen will show you how the values will be interpreted by the module – regardless of what the values look like to us ...

if you still can't get this worked out, you can give me a call sometime next week and I'll walk you through the setup step-by-step ... I'm teaching this week so this is not a good time for me to work on this ...

I hope this helps ...