Help newbie with OMRON

[ThomasLC]

Hi Guys!

As the Topic title says i am new to Omron and PLC programming. I just finished my last exam as an apprentice (Automation Technician). And we didnt do any Omron programming at all.
When i got back to work i was asked to make a PLC program with Omron CJ1M/CPU11 and a MAD42 module. Its for an airventilator system at the workshop on my factory.

I bought 3 Carlo Gavazzi current transformers which gives me a 4-20mA signal depending on the current that goes through the 3 phaeses, i then want to take the three mA signals and put them into my MAD42 module and scale the signal on the PLC. And then make a 4-20mA output signal from the PLC to my frequency converter (VLT2800)

But i dont know anything about programming analouge, so i thought maybe you guys could lead me into the right direction.

Im guessing i have to use some Math instructions but again, im not sure what im doing at all with this Omron programming.

If you have any further questions for helping me please ask!!
Thanks for your time, and help in advance.

 

[Lancie1]

It's for an air ventilator system at the workshop on my factory.

What is the goal, to control the speed of the ventilator fan, or to control when it goes on/off, or what? If you are controlling the speed, then what determines how fast it runs: temperature, humidity, number of required air exchanges per hour, or what?

Normally, you would use a PLC PID (Proportional-Integral-Derivative) instrtuction block to control a process variable such as temperature. I think the Omron PID insturction is called "PID(-)" or "PIDAT".

 

[ThomasLC]

What is the goal, to control the speed of the ventilator fan, or to control when it goes on/off, or what? If you are controlling the speed, then what determines how fast it runs: temperature, humidity, number of required air exchanges per hour, or what?

Normally, you would use a PLC PID (Proportional-Integral-Derivative) instrtuction block to control a process variable such as temperature. I think the Omron PID insturction is called "PID(-)" or "PIDAT".

The goal is to control the ventilator system. When the blacksmiths uses a velder or belt sander or anything else in the room the ventilator has to turn on. I want to measure the current with the carlo gavazzi current transformers. If the current goes higher than, lets say 1-2amps the ventilator has to start at 20% suction, and the higher the amps goes the higher the ventilator goes.

If the CG measures Amps -> Ventilator goes on

amps off -> Ventilator goes off after 5 minutes without a measuret current.

I hope you understand what my problem is.

 

[mendonsy]

As Lancie1 suggest, a PID instruction is one way to do it. Your requirements may be a bit more simplistic though.
You could just add the three analog inputs together to get total current draw then use the SCL(194) instruction to generate the analog output value.

 

[ThomasLC]

Ok thanks for your replys!!

I have read about the SCL instruction but im not sure how to put the data from the Carlo gavazzi current transformers into the SCL instruction? Is it with the MOV instruction? If i connect the current transformers to the plc some data have to show up somewhere, but i dont know where this is. Maybe in the PLC Memory??

I am very new to this omron so please have patience with me, and thank you for your time!

 

[mendonsy]

The data won't just magically appear. There is some configuration involved to set up the module correctly. You need to read section 7 of the W345 manual which you can download from myOMRON Europe.
http://www.myomron.com//downloads/1.Manuals/PLCs/UNITS%20CS%20and%20CJ%20Common%20Manuals/W345-E1-11%20CS-CJ%20Series%20Analog%20IO%20Units%20OperManual.pdf

 

[Lancie1]

If the current goes higher than, lets say 1-2amps the ventilator has to start at 20% suction, and the higher the amps goes the higher the ventilator goes.

Your room air quality is not proportional to the current being used. The current is only an indirect indicator at best. If you use this method, at times you will have 200% more ventilation than needed and at times 200% less than needed, due to the time lag between start of activity and dirty room air. You could probably do as well with a simple motion detector: if activity or movement is seen, turn on the ventilator.

As Mendonsy said, to use the current, simply read the current with a PLC analog input, scale it and move it to a PLC anlog output for your ventilator frequency converter signal-follower input (4 miliamps = 0 speed, 20 miliamps = 100% fan speed)