micologix 1100 & 1769 IF4 (analog)

Hi All,

I have just installed a micrologix1100 with a 1769 IF4 analog module connected, connected to channel 0 of the 1769 I have a 4-20mA / 0-16 Bar danfoss pressure transducer, the transducer is measuring around 7 Bar.

I have used a SCP instruction in my ladder but the value being displayed on I:1/0 (the 1st analog channel) is -57, I have checked the channel is configured for 4-20mA (in advanced I/O config) and is also set to raw data, and also that the DIP settings are on mA and not V.

I can't find any information on setting the module any further than I already have.

Starting from 'scratch', what is the raw data expected from a 4-20mA transducer measuring from 0 to its maximum ?

Thanks
Chris

See PDF below for data format values for your card.It should explain the error your seeing, adjust the SCP min/max values to match the cards data format values for 4 to 20ma.
If you are still having problems then post your code here and someone will that a look

You have to configure the card in oftware (best way) goto thr rockwell site & download the 1769 if4 document.

Couple things come to mind:
1. Is your 4-20 loop powered? (If an analog input if not getting powered it will sometimes have a value of -12 or -13 counts)
2. Are the + & - signal wires reversed?

If you have a 4-20 simulator, I'd give it 4ma and see what the input reads. it should be around 6240 counts.

1769-IF4 or 1762-IF4?

Thanks to evryone for the help.

I think I have made a basic error, using the SCP instruction I have my min input a 4 (as in 4mA) max as 20 with a corresponding scaled input of 0 & 16, where I should have the min & max input as the min & max raw data for the module.....

as for the rest

1. Yes its a 1762, not 9 : )
2. I have the loop powered I'll double check the + / - signal polarity

Follow-On Question to A-B Analog Scaling

I've actually got a 1769 AI Module (IF8), and need to know how to scale it to 0-35 gallons (i.e. 4ma = 0 gal and 20mA = 35 gal).

I've found in publication 1769-UM002 information similar to what you guys concluded for Chris. Page 3-11 shows a table for what the low and high are in either counts or what they called "Engineering Units". But for the latter, my value coming into the PLC is 4,000 to 20,000...which to me is still "counts" in a sense. I need to correlate that to 0-35 gallons.

I don't see any SCP instruction in RS Logix 5000 Ladder, which helped Chris (he was using RSLogix 500 I imagine). How do I convert my 4,000 to 20,000 (or 6241 to 31206 in counts) to match my "real world" (0-35 gallon tank). I would call that result "Engineering Units".

Thanks,

Arun

General form of scaling

EngValue = (RawValue - RawMin) * (EngMax-EngMin)/(RawMax-RawMin) + EngMin

In your case using the 4000 to 20000 count example

EngValue = (Rawvalue - 4000) * 35/16000

Use a CPT instruction to calculate.

Thanks!

All sorted now, thanks for all the help.

I have raw data min as 6241,max as 31206 with corresponding scaled input min 0 and max 16.

got an input of 10mA now and a resultant floating point of around 6 bar.

Thanks
Chris