1756-IF8A analog card always has value in channels

enbeya

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Join Date
Sep 2007
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canada
Posts
44
Hi all
I tried to find answer in the previous theads but did not, my problem that my input card analog 1756-8channels for AB logix 5550 configured it to 4-20ma and connected the channels to ma source as simulator using only 4 channels differential as it was in the manual but can not get any value changing in the channels data ,and some of them already reads some data even if its not connected.
any help will be appreciated
 
just a guess ...

double-check your wiring ... you need to install a jumper on the terminal block for each channel in order to use current sources as inputs ...
 
only your first channel (Channel 0) has been configured for current – the rest are still set up for voltage ...

also ... I'm very suspicious of the Firmware Revision that you have set up for this module ... you have 1.1 ... personally I've never seen one that wasn't a version 1.5 ... double-check that value by going through RSLinx to the module – then right-click it and look at the "Device Properties" screen ... if you find the Firmware Revision is different from what you have set up, then fix that part of your program and try again ...

 
just another thought ...

you're not using your analog output module to "feed" the analog input module are you? ... sometimes we do that for testing/simulation purposes ... IF (that's a big IF) that's what you're trying, I've just noticed that your analog output module isn't set up correctly ...

it's OK to connect "output" to "input" for testing - but we need to know that and fix the output module FIRST ...
 
the vision written on the input module is like this CAT.REV 1756-IF8/A
C01
AND IN MY CONFIGRATION ON THE FILE I SENT U I CHOSE ON WHEN SETTING THE CONFIG .
and for the out put card iam not using it as simulator i use different simulatot with variable pot
 
instant replay:

double-check that value by going through RSLinx to the module – then right-click it and look at the "Device Properties" screen ... if you find the Firmware Revision is different from what you have set up, then fix that part of your program and try again ...

do you know how to find the information that I'm talking about in RSLinx? ... do NOT (I repeat: do NOT) trust what is written on the label of your module ... the firmware might have been "flashed" to another version - and people usually (never?) bother to change the label ...

just for kicks - try setting the revision to 1.5 and see if it works ... it won't hurt anything - and you might get lucky ...

and just for discussion: the number on the side of the module that I'm talking about is in a dotted line - and marked "F/W REV." ... the reason for the DOTTED line is because a stick-on label is supposed to be placed there when the firmware gets changed ...
 
Last edited:
Hey RON yes i did what you said and the device propries said its 1.5 but when setting the card up I have only options from pulldown menu 1,2,3, no 1.5
 
I am trying to set up the card again and change the revision to 1.5 but does not even exist , is there any difference because when choosing the card mode I can find 1756-IF8 BUT WAT IS WRITTEN on my module is 1756-IF8/A
 
you set the ONE part as the "Major Revision" when you first install the card ... the FIVE part is the "Minor Revision" and it gets set on the "General" tab of the module's Properties Setup screen ... and they do NOT show a decimal point between the two settings - which confuses a LOT of people ...

fwrev.JPG
 
Last edited:
Ron,

although enbaya has Rev 1.1 selected for the module, his keying method is "Compatible Module" - so he OK with a 1.{anything} module.
 
now both says 1.5 revision after changing them to now 1.5 ,and the changed the channels 4-20ma all of them ,and the high sigal to 20 and low to 4 ma and the engineering high to 100 and low to 0 . and all the channels has data of 39.32076 value when I check them in my program with out any thing connected ,now i am going to connect my 4-20am simulator and try to change that vaule .
 

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