1756-IF8A analog card always has value in channels

Hi enbaya, perhaps I can help you....

1. When you are Online, do you see any Warning Triangles on your Analog Input Module in the IO Configuration tree ? and is the IO light on the front of the processor flashing ?

2. Your configuration looks correct to me, have you double-checked your wiring ? are you sure you have wired for "Differential" mode input ?
 
Hi daba thanx for the replay , I dont see any triangle and the I/O light is sold and not flashing .i will post how i wired the terminals
 
from daba:

although enbaya has Rev 1.1 selected for the module, his keying method is "Compatible Module" - so he OK with a 1.{anything} module.

well, maybe it's different on the analog modules ...

I'm basing my advice on what I've seen with the 1756-IB16I DC input modules in my lab equipment ...

I've got five that are F/W Rev. 2.2 ...

I've got one that's F/W Rev. 2.1 ...

I'll swap these around while the students are off to lunch for troubleshooting purposes ...

if the setup is for a 2.2, the 2.1 won't work right (note the "alert icon") even though the Electronic Keying is set for "Compatible" ...

note that I'm using a 1756-L55 processor and my RSLogix5000 is version 16.03 ...

21vs22.JPG
 
Last edited:
Absolutely right, Ron.

If the setup is for a 2.2, then a 2.1 WON'T work in the slot, even if Compatible Module is selected.

Here is the matrix...

Type Major Minor
Disabled Similar Don't care Don't care
Compatible Same Same GEQ
Exact Same Same Same



Note the GEQ in compatible mode, if setup is for 2.1, any rev 2 module will be ok. If setup is for 2.2 and you put a 2.1 in, it won't.

Holds true for ANY module
 
OK ... got it ... this is my "learn something new" for today ... I wasn't really looking at the "going the other way" effect ...

when I set it up for 2.1 - and then plug in a 2.2 - it works fine ...

thanks for the clarification ...
 
this is how i am connected to is from my simulator ,using pot risistor and all connected in series

neg power sup connected to pin 18
pos power supply connected to one lead of the Resis
other lead of resistor connected to the pin 16
and 18 connect to 15 jumper .when i put my amp meter I can see the ma goes up to 20 ma .

3.jpg
 
I see nothing wrong with the way you have it wired, although your terminal numbers used are for channel 3, not channel 0.

I find it disconcerting that all channels are showing exactly the same numbers, was that picture saved when the inputs were disconnected ?
 
yes but wen i connected it the way it wat like above .and checking all channels cos I only connected to ch3 but still all read 39.32 and when i break the cicuit and put my am meter it reads ma uo to 20am as i change it but the reading s stuck at that value 39.32 .
the only thing left to simulate from the analog out card if the sma them my card is fautly .
 
I was thinking along the same lines, card faulty ?

Perhaps a call to tech support is needed, or a browse of the Knowledgebase might throw some light on this.

Have you tried this in Single-Ended mode, using IN-0 and RTN-0 as your current input ? (You will need to delete the module from the tree and put it back in the S/E mode).

Everything you have showed us looks fine.
 
thanx daba daba and Ron for your help I really apprciate every word you wrote and got alot form it ,i will call tech and see if he can its 100% faulty card .
thanx again guys
 

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