1769-IF8 Module for reading current

Could someone point me in the right direction for writing logic for my project at work? I want to monitor the current draw of a dc compressor motor. I am using a DCT-200 transducer with its output connected to a 1769-IF8 (channel 0) input module. I just finished my fourth class in PLCs 2 months ago and we covered something similar in class. Now I'm in the real world and I've gone brain dead. Could someone help please? - aleast get me started in the right direction.

Thanks

Okay, so that's an Automation Direct current transducer. It has a 4-20 mA current loop output.

Are you asking for help wiring it up, or writing code that 'monitors' the input channel ?

I think I have it wired correctly. I just need help getting started writing the code.

To get started, write out what you want the code to do, in plain English.

I think what you need is to take raw 'counts' from the 1769-IF8 module and scale them so that you have 'Engineering Units' of amperes.

The 1769-IF8 module works with both the MicroLogix 1500 and the CompactLogix controllers, so start by posting which controller you are using (and in the case of CompactLogix, which firmware revision).

If you can provide any information about how you have configured the module, that would help as well.

Are you getting any input data at all from the module ? With no current flowing through the sensor, you should be getting a 4 mA signal on the analog input channel. That's the first point you need to determine the scaling of the input signal.

The second point is to calculate or measure how many 'counts' you will see in the input data register for the highest measured current.

I want the code to read the amount of dc current flowing through the wire that the transducer is monitoring and eventually show the results, in real time, either in analog or digital format on the PanelView plus 600. The project requires a "Pass/Fail" acknowledgement in that if the current draw is more than 15.00amps, an output for "Fail" will be energized and if the current draw is greater than 5.00amps and not more than 15.00amps, an output for "Pass" will be energized. These 2 conditions will only happen after 3 test cycles; that is, after the current is monitored for 3 on/off cycles(these cycles are already written using timers), the "Pass" or "Fail" output will energize. But, if at anytime during any of the test cycles the current exceeds 15.00amps, the "Fail" output will energize.

I am using CompatLogix L43 firmware revision 19.11.

The 1769-IF8 is configured the sam for all channels - 4-20ma, 60Hz, Engineering Units, and 130ms real time sample. It is a series "A" revision 1.1 module in slot 5.

The input at the analog module is 4ma and if by number of points to count you mean the maximum amount current to read, that would be 20 for 20amps. It can be more than that if it is easier to compute. It's just that if any of the compressors reach 18.00amps they're going to be producing a good bit of smoke if not fire also. They are manufactured in China and cost only $7 each.

The 'Engineering Units' setting is good, since its easiest to correlate with the actual number of mA coming from the transducer.

With the DCT-200 connected to the 1769-IF8, you should be seeing 4 mA in the loop, which means the Local:I.Data.Ch0 value should be around 4000.

Exactly which model of DCT-200 are you using ? You need to know how many mA will come out of the instrument loop circuit for a given number of Amperes flowing through the measurement side.

I'm going to recommend the Scale With Parameters (SCP) add-on instruction from the RA sample code library. That will allow you to easily convert milliamperes of transducer current to amperes of compressor current to use in your testing logic.

I'll post an example shortly.

Attached is a PDF file report for a simple example of a scaling and threshold measurement routine.

Yes, the transducer is a DCT 200-42-24-F. The sample code looks like what I need to complete this phase of my project. Thanks ever so much. When I finally ge the project completed, I'll post it here for anyone who would like to see it. Thanks again!