SLC analog

I have just got a 1746-NI8 (8-channel analog input)

I have 0-5vdc on any one of the channels, tried them all, the dip sw are set to voltage, I thought it may have been the way I wired it but, I changed it and installed a NI4 and it works great...

Also why does it show 16 channels? here is a screen shot or am I just reading this wrong?

any ideas?

When you configured as class 3 the first 8 words are data and the next 8 are status words

The status bits are where "Instrument Health" information can be obtained. I had an application that used status bits 12 (open circuit), 13 (over range) and 14 (under range) as alarms without having to add ladder rungs to check for out of range conditions.

Thanks guy's...I had that one screwed up, but we (me and PLCS.net ) got it working.

So when I bought the new card, if I did not get a class 3, I would not of had to configure it?, in the past I have only plug them in then started programming

but anyways thanks for the help, its working like a champ

So when I bought the new card, if I did not get a class 3, ...

Click to expand...

actually it’s the same module when you buy it - but you can select whether to use either “Class 1” or “Class 3” operation when you put the module on the I/O Configuration Table ...

besides the “extra words” on the Data Table, you might want to take a look at the “User Set” scaling range feature when you have some spare time ... sometimes it comes in handy ...

Hi Jack alert

Hi Jack (sorry I couldn't help it).

Ron/GIT and anyone else, I have never fully understood what is going on with my NI8 card that I described in this post:

http://www.plctalk.net/qanda/showthread.php?t=26976

but I have also found out that a sister plant is using it in a way that I can't get it to work (reading below 4mA) in the NI4 data format. Any clues? I can use engineering units and rescale my SCP but I really wanted to understand why I never can get this to work but someone else can. Any help/explanation would be greatly appreciated.

Greetings brucechase ...



right now I only have time to SKIM through your earlier thread ... one statement in there sort of “jumps out” at me ...

What I did notice is that they are not using a NI8 card – they are using a NIO4I card (but the NI4 card should be the same).

Click to expand...

I’m not 100% sure that your “should-be-the-same” assumption is correct ... I’ll work on this in the next few days ... I already have a 1746-NI8 card on hand - and I think that I can round up a 1746-NIO4I module soon ... what I’m planning to do is a side-by-side comparison of their operations ... I have plenty of 1746-NI4 modules in the lab ... if I can’t get the 1746-NIO4I, then I’ll do the best I can with what I have available ...



my best guess right now (pocket change only) is that the (configurable) 1746-NI8 “works different” than the (non-configurable) 1746-NIO4I module - even when the configuration is set for NI4 operation ...



at least that’s what I EXPECT to find ... anyway ... I’ll let you know what finally happens ...



thanks for an interesting question ...

Ron, thanks for the clarification, these are very nice cards they have a lot of features compared to the NI4's





Bruce, I'll let the pro answer ,

Ron Beaufort said:

... I’ll work on this in the next few days ... ...

Click to expand...

I've attempted to answer bruce's question in his original thread ... click here if you're interested ...