1762-IF2OF2 Analog Input Problem

davidgay

Member
Join Date
Jun 2002
Posts
29
Ladies & Gentlemen:

I have the following configuration:

Micrologix 1200 Rev C 1762-LW40BWA processor with one 1762-IF2OF2 analog i/o card

I have hooked the hardware up per the installation manuals, i.e. the ribbon cable is attached between the processor and the i/o card.
I have brought up a new project in RSLogix 500, configured the processor, added the i/o card by reading the i/o config.
I have set the ADV Config. such that all i/o are 4-20 ma & Raw.
Ensured that the internal dip switches on the analog card are in the 4-20 ma position.
Supplied a known input to In0 (+) and In0 (-).
(I have a meter across the inputs so I can see the signal is present.)
I have cycled the power to the processor repeatedly.

The problem is that when I go into RSLogix500 and examine the input values (I can see that the Input and Output words are displayed in the O and I datafiles) but there doesn't appear to be any value in the input bits for the input (i.e. all the input bits are zero) not a binary pattern for the value converted from the input signal.

The Input data bits are as follows:

Data Word 0 thru 4 are all zero for the module.
Data Word 4 Bit 5,6,1 and 0 are ones for the module.
Data Word 5 Bits 15,13,7 and 5 are ones for the module.
All other Bits are currently zero in words 4 & 5 for the module.

This seems to indicate that the current is below the threshold for the inputs and outputs regardless of the value on the meter input.
I have modulated the ma signal in from 2.3 ma to 8.5 ma and the inputs do not change.

Additionally:


1762-IF2OF2 <----> Raytek I/R Pyrometer

IN0 (+) -------------MA (+)

IN0 (-) -------------MA (-)


I have not worked with this combination of hardware before, and have searched thru all of the available on-line manuals, but appear to have missed some critical step. Is there some bits that need to be "turned on" so that the processor will use the module (i.e. an "enable")?
Is there a setting in the IOS function file that needs to be set or what??

I would appreciate any help or insights that could be provided.

Thank you for your time and input.


David Gay
 
I would, as a troubleshooting method, set up one of the analog output channels for 0-10 volts(easiest to read with a meter) and see if you can get voltage at the output. This would at least tell you if the problem is in your programming/configuration.

I noticed you are talking in bits.....You can look at the I/O files in decimal.
When you open your data file look in the lower righthand corner. Pull the dropdown box labeled "radix" currently at binary to decimal.
 
I doubt someone who would write such a detailed post would make this error - but, just as a thought:

You said: "I have a meter across the inputs so I can see the signal is present." If this is a current loop, the meter should be in series (not "across" or in parallel) with the input signal. Could this be your problem? If the meter is connected the way (I think) you described, the meter is shorting out the signal to the module.
 
Respondees:

Thanks for your inputs, I really appreciate them.

First, I'll try the 10V setup. The reason I was talking in bits was that these specific bits are on in the input words, thanks for the info on the radix change, I was already aware of it, but since selected bits in the input word are "reserved" or unused I thought it better to supply the info in bit format... Thanks Again!

Additionally, sorry for the terminology faux-pas the meter is in series, but thanks for that... you never know with electrical wiring when thats the problem...

I don't seem to "see" the current inputs... do I have this wired correctly?

Raytek Ma(+) ----> Terminal block ----> IN0(+)
Raytek Ma(-) ----> Terminal block ----> IN0(-)

Do I need a "pull-up" resistor or something?

I'm not very good with the wiring... more of a programmer type... give me a screwdriver or wire pliers and I'm really dangerous.. LOL



Thanks Again for your responses.
 
davidgay said:
First, I'll try the 10V setup.

I went through a quite lengthy battle with a Compactlogix 1769 analog output card and I found this the easiest to determine....

davidgay said:
thanks for the info on the radix change, I was already aware of it, but since selected bits in the input word are "reserved" or unused I thought it better to supply the info in bit format... Thanks Again!

I wasnt trying to insult your intelligence :) I thought if you are new to RSLogix, it might be a hulpful tip.
 
The book says that configuration changes are sent to the module only when "going to run" mode - did you cycle power after you made the configuration setup changes - and then downloaded the program?
 
Sorry 93 if I gave you the impression that the reply was "bad" or anything, I just wanted you to know I was already aware of the radix stuff. I am in the process of checking out the 10V setup now... I really appreciate all inputs and feedback... you never know what has or has not been tried when doing problem solving... and any responses are always gratefully appreciated.

Thanks Again!
 
davidgay said:
I have hooked the hardware up per the installation manuals, i.e. the ribbon cable is attached between the processor and the i/o card.
I have brought up a new project in RSLogix 500, configured the processor, added the i/o card by reading the i/o config.
I have set the ADV Config. such that all i/o are 4-20 ma & Raw.
Ensured that the internal dip switches on the analog card are in the 4-20 ma position.
Supplied a known input to In0 (+) and In0 (-).
(I have a meter across the inputs so I can see the signal is present.)
I have cycled the power to the processor repeatedly.


Ron- That was the first thing I thought of, because the solution to my problem with the 1769 analog output card was just that, a proper sequence of setting bits and cycling power.
 
Respondees:

Thanks for the input about cycling the power, I have cycled power several times to no avail.

Am I doing the setup in the proper sequence or am I missing something?

0) set dip switches on 1762-IF2OF2
1) create new RSLogix project
2) configure Processor
3) read I/O config
4) perform ADV Config for the 1762-IF2OF2 changing from 10v to 4-20ma
5) save configuration
6) download to 1200
7) exit RSLogix
8) cycle power to 1200
9) bring RSLogix back up and go Online
10) examine I/O values either in the data files or thru CDM

Again, thanks for all the responses.
 
One more grasp at one more straw:

Are you putting the processor into the run mode? Very few types of processors will read their I/O while in the program mode.

Best of luck - off for tonight.

Ron
 
Ron,

Thanks for the further inputs, I'm really scratchin' my head with this...

Does the Micrologix 1200 not get the configuration of the expansion cards when you create the new project and read I/O config. in Offline mode before you initially download the ladder logic & configuration to the processor? I'm really stumped on this 1762-IF2OF2... I just finished configuring an expansion module with digital I/O on an identical processor and didn't have a bit of trouble with it... guess I'm just not holding my mouth right... I'll continue working on this and let everybody know what's up (as soon as I can figure that out myself)

Anyway, thanks again for the responses and I really like your "2B or Not 2B".... very imaginative! Thanks again!
 
my two cents

Have you examined all of the AB manuals with a fine tooth comb. I am not trying to be critical in any sense of the word, its just that. I have been burned so many times by not reading all of the A/B fine print.

ex) I had a module in a remote I/O rack once, and didn't have the correct version of the remote I/O adapter module, and the module didn't work. Everything else in the remote rack worked, and nothing in the I/O module manuals said anything about the remote ASB module version problem. Nor did my ASB module manual say anything. If I had bought the latest ASB module and know to go and down load the new manual for this module, and read the very fine warning, printed on the wrong page of this new manual. Then I would have known. Good thing that tech support guy (came real short of calling me an idiot for not knowing this) helped me out. sorry, man, I try not to complain about AB, but .... so many wounds to supress.

Also, some modules don't auto config correctly. Try configuring the module manually just like the manual says.


3rd, you probably already know this, but most Analog modules need to be configured by writing a configuration word to them. Make sure this configuration word is set up correctly, and writing to the card.

4th, did you try the module in the main rack yet?


just my two cents. Hopefully I am on the right page. If not, then just ignore.
 
Did you check for voltage output yet? If so and still no luck, I agree with ganutenator, put the analog card in the main rack (so to speak). I am not that familiar with Micro 1200 but I have worked with the 1500 and of course the SLC's.

When you say:
when you create the new project and read I/O config. in Offline mode before you initially download the ladder logic & configuration to the processor? I'm really stumped on this 1762-IF2OF2...
Do you mean that you are creating a new project with no code, do a read I/O config, and then downloading your offline program?

If so I dont think that you are getting the "read I/O config" into your offline file...

I have never used the read I/O config. I have seen it, but i usually just select the module manually.

I am becoming really curious!!! :confused:

Keep us posted!
 
Friends and neighbors,

To help some of you visualize what this guy is up against, take a look at the hardware at: 1762-IF2OF2 Manual on Adobe reader page 7 of 24. There is no “rack” for the MicroLogix1200 - the expansion modules for this system just snap onto the DIN rail with the processor and are connected to the processor by a ribbon cable.

Next, go open a new project file in RSLogix500. Highlight “MicroLogix 1200 Series C” for your processor type and click OK. Double-click the IO Configuration icon. You won’t have the hardware available, so you can’t automatically “Read IO Config” – but you can just double-click the 1762-IF2OF2 module to insert it into “slot” 1. Now highlight the module you just added and click the “Adv Config” button to get to the module’s Advanced Configuration screen. Go to the “Analog Configuration” tab. There are the four channels (2 inputs + 2 outputs) that David is trying to configure and use. Before you change anything, take a quick look at the numbers on the “Generic Extra Data Config” tab. Now go back to the “Analog Configuration” tab and set each of the input and output ranges to “4 to 20 mA”. Leave the Data Format settings at “Raw/Proportional”. Click the “Apply” button to nail these values down. Now take another look at the numbers on the “Generic Extra Data Config” tab. They have been changed to reflect the new module configuration that you have specified. The numbers in this “configuration file” SHOULD BE automatically written to the module when the processor goes into the run mode. At this point you should be able to go to the Input and Output tables and see the channel locations. Usually, decimal radix is the best way to look at these. Now if you actually HAD the hardware, you would make sure that the “Current/Voltage” selector DIP switches on the module are set “ON” to use current inputs. You would save and download your program to the processor. You would cycle power to the processor to initialize the module. If the current is actually flowing through “Channel 0” on the module – as it seems to be from the meter indications in David’s posts – and if the processor is in the “Run” mode – then we should see a reading at location I:1.0 reflecting the current flow.

Now I’ve only worked with a MicroLogix1200 once – and that was several months ago – but I’m 99% sure that I’ve got all of these steps right.

Eventually, somebody has GOT to suggest that maybe the hardware might just be defective – but that somebody won’t be me.

THIS JUST IN: David asked the question:
Does the Micrologix 1200 not get the configuration of the expansion cards when you create the new project and read I/O config. in Offline mode before you initially download the ladder logic & configuration to the processor?
Whoa, hold on there, David. When you “Read I/O Config” offline, what you’re doing is GETTING the configuration currently in the module – FROM the module. What you need to do is set the Advanced Configuration as noted above – then DO NOT read I/O Configuration again before you download. If you’re doing what I think you just said, you might be over-writing YOUR configuration settings with the default (wrong) settings in the module – and then downloading the wrong stuff. But then again, maybe we’re just misunderstanding each other through these posts.
 
Respondees:

Well the saga continues... I have set the card for 10v Input/Outputs and forced the outputs all high (output should be approx 10v) and I get the expected correct output voltage, so I changed everything back to 4-20ma and with the outputs forced all high again checked the outputs and found approx. 20ma... so I got the bright idea of routing the output directly to the input (hard wired) to check the inputs and guess what no input values changed in the input data file... I am beginning to suspect that the input side of the analog card is defective... after all if the outputs work right (both voltage and current) then the card is configured properly... right? And the outputs should be perfect matches for the input side of the card, right? I am going to get another analog card from AB and check it .vs. the results from this card as my next step in figuring out what is wrong with this.

Thanks for the inputs I really appreciate you guys giving me your inputs, keeps me "on the straight and narrow" so to speak.

Ron, I've done each of the steps you described and still the inputs don't show any change... I think your right... DEFECTIVE CARD!

Gan & 93, thanks for the inputs, I'm gonna get with AB and see if the card is really the problem not the config.


Again, BIG THANKS to all who responded... maybe sometime I can return the favor.
 

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