Analog Input on wrong channel

[Unlucky]

Hi all I am having a very weird problem with my control system.
I have flex I/O communicating via control net to a RS5000 processor.

The analog card is a 1794-IF8IH Hart

Here is the problem.I noticed a bad input on channel zero, I have penty of spares in the cabinet so I just moved the transmitter and called my programer to reassign the input.

When I got to the control room i noticed the input on channel one was now reading bad, long story short.....when i simulate an analog signal with my meter on channel zero it shows up on channel one. Simulate on channel one it shows up on channel two. Same for channel three, that is as far as I went. I'm going to assume that the whole card is this way. The whole card is just Temperature transmitters(loop powered) that don't control anything so it's not killing production.

Here is what has been tried to fix the problem.
I have verified the wiring is correct.
I have swapped the card .....no help
I have swapped the base......no help

I have asked my programer to check the configuration at least five times and he says it is right.

One of the big problems is I can't get into the program, it has to be done by someone else.

Please tell me that this is a common problem that is easily fixed.

 

[I is a noob]

Maybe the PLC is correct. Could the HMI need to be shifted to reflect field changes?

 

[Unlucky]

Maybe the PLC is correct. Could the HMI need to be shifted to reflect field changes?

According to the programer he was looking at the raw data on the card as I was simulating the signal.

 

[micky]

According to the programer he was looking at the raw data on the card as I was simulating the signal.

You kinda confused me. Is the raw data in PLC reading right and the HMI wrong? Or are they both reading the same but wrong?

 

[Unlucky]

You kinda confused me. Is the raw data in PLC reading right and the HMI wrong? Or are they both reading the same but wrong?

The raw data in the PLC is reading on the wrong channel

As in I am hooked into the card on terminal zero and have a jumper on terminal one to the common row( the middle row on the base ) I have the other side of the meter attached to the third (power)row. The meter is on simulate the leads are hooked up right, but instead of seeing the input on channel zero on the card it is showing up on channel one.The milli amp value of the signal being read in the program is the same as I am simulating. I have repeated this for the first three channels and get the same results. The reading in the program while looking at the card is always one channel greater than the physical connection.

 

[bigbuckaroo]

Check the terminal designations on the Flex instructions sheet. The terminal numbers are sometimes not what one would expect.

 

[Ken Roach]

If somebody else is looking at the computer screen, it's hearsay.

What is the exact tag name that you are getting a simulated data value on when you connect to Terminal 0 on the FLEX terminal block ?

Every data table I've seen agrees with what you expect: Terminal 0 is Channel 0 and should show up in Register 0 in the Input data table.

I've never heard of anyone claiming that an analog module had "shifted its data", but I've mis-read tag names plenty of times.

Are you using a HART simulator, or an ordinary 4-20 mA simulator ?

It's a big world out there, with room for things as strange as this. Let's check all the horses before we go crying zebra.

 

[OkiePC]

I've never heard of anyone claiming that an analog module had "shifted its data"...

I have seen this once (twice actually, identical circumstances) with a module from AMCI in a PLC-5. Because I had removed digital cards and put the AMCI double-wide module in the same slots and I had left some bits with "1"s in the output image where the new card resided, the 4 channel data values were periodically shifting (rotating) from channel to channel. It happened about once every second or two. It was very weird. Clearing the output image for the affected slots and power cycling the controller fixed it.

I am not saying you have module weirdness like that, but it isn't impossible (just extremely rare).

 

[Unlucky]

I am using a Fluke Process meter model 789 on simulate because it is a two wire temperature device I am simulating(Rosemount). We use about forty of these cards in our system so I can wire them in my sleep. If it were an externaly powered device I would use the meter on source and put it on terminals zero and one with no jumper.

I know the wiring is right. As Mr Roach has stated I would bet about anything that it is an addressing problem but my programer says he has checked it about six times and it is right.

We have worked together for over a year on this project and I really have no choice but to beleive him as he is in Canada and I am in Indiana.

I still am leaning this way because as Mr Roach said "if I don't lay eyes on it and its still broke I can't rule it out."

He has done silly stuff before with analog outputs being referanced in more than one spot......control valves really don't like that.

It took some harsh words and some minor intimidation before he found it. Maybe I will have to drive North.

 

[micky]

Or maybe post the program here and have another set of eyes look at.