Which PLC for just 1AI & 1AO signal?

[ckchew666]

Hi,

We have a very small project using PLC to control the pump to maintain a constant pressure for a water jet in a system.

There is an analog input from the pressure sensor (4-20mA) and output (4-20mA) is to a drive (to control the pump).

When the input from the pressure sensor is low, the pump must run faster to maintain the pressure. The pressure is fix and not adjustable.

Customer specified for either OMRON, Yokogawa or AB. Which ever cheapest. But I guess OMRON is the cheapest....but I'm not sure which model is suitable...can anyone please suggest.

No network or scara/touch screen.

 

[Andybr]

Why do you need a PLC at all for this? Most modern drives provide at least PI control for this type of application so you should be able to do everything you require in the drive.

 

[Ken Moore]

Why not a single loop controller? Small, inexpensive, and you have a display of all your parameters. You can also easily place the loop in manual, and do trouble shooting, maintenance etc...

You could use a ML1200 with an analog module, but the single loop is cheaper, and in my opinion a better choice for the application.

 

[BobB]

Why do you need a PLC at all for this? Most modern drives provide at least PI control for this type of application so you should be able to do everything you require in the drive.

Agreed.

If you have to use a PLC, Omron CPM1A is probably the cheapest but I would certainly tackle the job with a drive only.

 

[nonuke]

Please take a look at the attached example "Complex application 2".
This is the simplest way

 

[Stephen Luft]

Are those the only options that the customer will accept?

 

[ckchew666]

Thanks for all the replies

Where's the attached sample?
Yes, customer insists on the PLC to control the simple (1AI, 1AO) pump machine.

Looking the price for CPM1A + expansion module, we are thinking to checkout the PICO controller, I think it's cheaper than CPM1A. It has 4AI & 1AO, we never use/see any PICO before....will get the price from Rockwell on Monday

The CPM1A + 1 MAD01 cost around RM1800 = USD450.

 

[TConnolly]

AB has a power flex drive that has a full blown ControlLogix processor on board.

 

[BobB]

Have a look at the Mitsubishi Alpha2. It is a smart relay with analogues, RTD and thermocouple inputs and you can program the screen display.

 

[Eric Nelson]

Looking the price for CPM1A + expansion module, we are thinking to checkout the PICO controller, I think it's cheaper than CPM1A. It has 4AI & 1AO, we never use/see any PICO before....will get the price from Rockwell on Monday

Also remember that the Pico is just a Moeller Easy in disguise, so be sure to compare pricing from both... :nodi:



-Eric

 

[ckchew666]

Bob: Thx, i'll check it out also.

Eric: Wow! I do not know that until u tell me PICO is from Moeller Great info, I'll check out the price with them as well. Not sure if you know this - jst to share, the safety switches/push buttons selling by Rockwell, it's actually from Bartec

 

[ndzied1]

Yes, the Pico is the Moeller Easy. One thing to know is that you cannot use the AB software on the Moeller brand device and you cannot use the Moeller software on the AB brand.


In order to get an analog output, you need to have a Moeller Easy 820 or 822. I don't know what the equivalent Pico numbers are.

 

[ckchew666]

Yes, the Pico is the Moeller Easy. One thing to know is that you cannot use the AB software on the Moeller brand device and you cannot use the Moeller software on the AB brand.


In order to get an analog output, you need to have a Moeller Easy 820 or 822. I don't know what the equivalent Pico numbers are.

It's okie, i'll chk with moeller. Thx for ur info.

 

[Chuckmcc]

Unless you need HMI, then a single drive & sensor combo is the most practical.

 

[swimmy67]

For a small and reliable PLC, use the Allen Bradley MicroLoxic 1000 Analog model.

Part Number: 1761-L20BWA-5A or 1761-L20AWA-5A

Cost is cheaper than Omron or Mitsubishi. Has Two analog input, voltage or currend selectable. One analog output, voltage or current.

Thanks,
Swimmy67