SLC 500 Analog I/O

Hello Programmers,

I am new into the analog programming world. Please excuse any errors or mistakes.

I created a program that would scale my 1746-NT4 Thermocouple/mV Input module. Then I would like the input CHL 0, 1, 2, 3 to trigger 1746-NO4I Analog Output Module.

The program is able to see the analog input but does nothing to the analog output. Any tips or modifications are greatly appreciated! THANKS!

Is a simple program straight forward that there is no need for accuracy, I am just making a test bench to test modules in the future. I have 500ohm resistor across my output module to verify DC Voltage from the 0 to 20mA.

Thanks for your help

There are no parameters entered in the SCP

What parameters are you reffering too

A post of the project file (.RSS), zipped of course, forum rule, would be better than the project report, easier to see the wood from the trees....

Maybe I'm looking at something wrong. I don't usually use 1746 modules.
4-20mA output on a 1746-NO4I is listed as 6,242-31,208.
On your SCP to your outputs you scaled 10 as the min, and 10 as the max. To get a true full scale of your outputs, those need to be changed.

daba said:

A post of the project file (.RSS), zipped of course, forum rule, would be better than the project report, easier to see the wood from the trees....

Click to expand...

Please feel free to modify, I created this as a starting point.

I can see what the problem is.....

Your 4analog inputs look fine, scaling into N7:0,1,2, and 3.

But your analog outputs don't look right...

You are turning on bit 0 of N7:5,6,7 and 8 for specific values of N7:1,2,3 and 4.

This will result in N7:5,6,7 and 8 only containing either 0 or 1, depending on the EQU tests.

Then you are feeding that 0 or 1 into the output SCP's with the input scaling 0-21, and the scaled outputs 10 to 10 !

Since the inputs will result in scaled outputs of 10 for every channel, they aren't going to move.... even if you apply 0 or 1 to the SCP inputs.

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Questions :-

1. What do you mean by "...trigger the output module." ?

2. Why are you picking up specific values of analog input ?

Please explain exactly what the code is trying to do ....


ADD : dburnum also got it while I was typing....

As easier solution per input would be to use a single SCP per input/output. The inouts would be scaled to the temperature range you wish to measure and the "scaled outputs" would be set to 6,242 on the MIN, and 31,208 on the MAX.

dburnum said:

As easier solution per input would be to use a single SCP per input/output. The inouts would be scaled to the temperature range you wish to measure and the "scaled outputs" would be set to 6,242 on the MIN, and 31,208 on the MAX.

Click to expand...

I would do that too, simply map the analog ins, to the analog outs....

But the code is looking for specific "trigger" values, presumably to ?enable? the analog outs when the ins reach a threshold ??

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Questions :-

1. What do you mean by "...trigger the output module." ?

What I want to achieve is to turn on my analog output from N7:0,1,2,3 using the thermocouple data

2. Why are you picking up specific values of analog input ?
I did that just to experiment nothing concrete

Please explain exactly what the code is trying to do ....

All i want is to test functionality of the analog input and output. Making sure I can measure mA from the output module while the thermocouple CHL are enable.


ADD : dburnum also got it while I was typing....[/QUOTE]

silvaj17,

Did you get this solved?

I am curious. When you did the configuration on your 1746-NT4, what Data Format did you use?...and did you make sure the channels were enabled?

What temperatures range do you wish to measure by a thermocouple?

What do you expect for an Output? I seen from your initial post 4-20mA, but do you expect that one channel should read 4mA until a threshold is reached and then may output the mA once its reached that threashold?

dburnum

OK...I decided to download your configuration to take a look at it. Rungs 1-4 will look at the inputs as -10*F to +10*F and scale those temperature to -1000 to +1000. Those are a bit on the cold side for just general testing, but its your test application.

Rung 5 will move a 0 into N7:4, when...and only when it is equal to 10, with which a scale of -1000 to 1000, is .01*F which is close to 0 anyways.

Rung 6 looks at the N7:4 file to scale it, and its input...remember N7:4 was scaled -1000 to 1000, so its only looking at the small range of 0 to 21, but you are scaling it to an analog output, so 0-21 represents 0.0*F to 0.21*F...that's on the SCPs input parameters, but your output is scaled 10 to 10, which as stated earlier 4-20mA output data full range is 6,242 to 31,208, so 10 represents close to 0mA output.

Hopefully by picking specific rungs and describing what your logic is actually doing, may give you some insight to what changes you wish to make, so that it performs what you wish it to.