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Dietrich Thomys
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Join Date: Oct 2007
Posts: 1

PLC simulation

10/09/2007 3:48 PM

I need to simulate the analog inputs on a PLC in a training session. I have seen the mA unit that was discussed but need a multiple volt source as well. If it needs I will purchase. But rather get info to make a unit to do the simulation. So if anyone has a circuit for old mA mV/V analog source units it will be appreciated.
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Pathfinder Tags: analogs PLC source
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Vulcan
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Philippines - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Engineering Fields - Control Engineering - Who am I?

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Location: Northern Mindanao, Philippines
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Good Answers: 53
#1

Re: PLC simulation

10/10/2007 12:10 AM

What do you need to do? I created a simulator for our PLC-based (Allen-Bradley) controls using no modules at all. Everything was simulated in the program.

To simulate a motor start/stop, we merely used the motor output as the "motor-running" feedback. We used the same technique for valve open/close feedbacks.

For analog inputs/outputs, we used word addresses. For example, in a temperature controller, we used the output for the control valve (0-100%) and converted it to temperature (0-200°C), and used that as the input to the controller. Later, to make it a little more realistic, we put damping on the temperature conversion to slow it down. As we gained experience, we improved the program to make the simulator a little more sophisticated.

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PWSlack
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#5
In reply to #1

Re: PLC simulation

10/11/2007 6:18 AM

Quite.

Complete water treatment plants have been simulated in this way. The PLC's main program doesn't care what it is controlling. The plant simulator can be turned off and the 'real' plant switched on by toggling a single bit.

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Anonymous Poster
#6
In reply to #1

Re: PLC simulation

10/11/2007 9:09 AM

Vulcan,

i got interested with your feed back.

I'm from Philippines too and working at Middle East.

If you have time contact me at email below.

Thanks,

nlparedes2006@yahoo.com
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Vulcan
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Philippines - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Engineering Fields - Control Engineering - Who am I?

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#7
In reply to #6

Re: PLC simulation

10/12/2007 11:32 PM

Well, Mr. Paredes? I responded to your request but you probably don't read your yahoo email. How may I help you?

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agus_kuds
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Join Date: Oct 2007
Posts: 5
#2

Re: PLC simulation

10/10/2007 4:21 AM

I think you can build your circuit with ADC, you can search the reference by google or www.national.com. Usually I used ADC0804. good luck
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Anonymous Poster
#3

Re: PLC simulation

10/10/2007 9:40 AM

FasTrak SoftWorks has a PC based simulator for Siemens 505, Modicon, and CTI 2500 PLCs. There is also a built in I/O Simulator used to manipulate I/O values, which can be run in batches to simulate analog inputs and outputs. In your training class, you could set up a batch that corresponded with the behavior of your mA unit, without actually needing the physical device on hand. I handle Tech Support at FasTrak. You can call me at 262-238-8088 ext 1030 or www.fast-soft.com I can give you the detailed technical info on the simulator to see if you can use it in your training.

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tkirk
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Join Date: Sep 2007
Location: Denver, Colorado, USA
Posts: 6
#4

Re: PLC simulation

10/10/2007 4:45 PM

A 12V wall wort connected to a few resistors configured as a voltage divider to set the voltage you need should work just fine. Add a potentiometer (adjustable resistor) with a knob for adjustment to the voltage. If you want it to be more stable, add a voltage regulator chip between the wall wort and the voltage divider.
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pwr2thepeople
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Join Date: Aug 2007
Location: Indiana, USA
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Good Answers: 61
#8

Re: PLC simulation

10/23/2007 2:45 PM

I usually use a second PLC with milliamp analog outputs connected to the inputs of the training PLC. I can program them to do anything I want, or even to run a variety of values automatically. For voltage inputs, simply put a dropping resistor across the input terminals.

This is particularly useful in troubleshooting and fault analysis training. I can set up a program (complete with abnormal indications) on the source PLC beforehand. The student only has access to the training PLC, and has to determine what the problem is, and how to fix it.

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Anonymous Poster
#9
In reply to #8

Re: PLC simulation

10/24/2007 3:15 PM

Thanks that is a good idea. All I really wanted to get is a mA and Volt source calibration circuit. It helps when testing loadcells and finding were the fault is much faster. I had to many Analog cards blow and this will just make it a bit quicker to fault find on whole cct.

Thanks again
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agus_kuds (1); Anonymous Poster (3); pwr2thepeople (1); PWSlack (1); tkirk (1); Vulcan (2)

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