pid vs. plc selection

maintenanceman38

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Join Date
Mar 2008
Location
Texas
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I need a plc controller to handle 12 pid zones. I do not have a problem with programming yet. as I can do AD and AB. but my problem is the price. Because what I want to do, Costs way too much to use a HMI and input 12 thermocouples. Does anyone know of a PLC that is is cheap as the AD brands and can handle multiple PID loops without a bunch of expensive thermocouple cards? or even one plc that can have one card and connect to an HMI? I am controlling heaters a simple pid event. thanks.
 
Define cheap. You could by individual temperature controllers for each, but they would run you 300-400 each. Sometimes you just have to bite the bullet, and spend the money. Specialty I/O modules (RTD, Thermocouple, etc...) are always pricey, compared to discrete.
 
maintenanceman38 said:
I need a plc controller to handle 12 pid zones. I do not have a problem with programming yet. as I can do AD and AB. but my problem is the price. Because what I want to do, Costs way too much to use a HMI and input 12 thermocouples. Does anyone know of a PLC that is is cheap as the AD brands and can handle multiple PID loops without a bunch of expensive thermocouple cards? or even one plc that can have one card and connect to an HMI? I am controlling heaters a simple pid event. thanks.
Click to expand...
Horner has the XL6.
PLC/HMI combo and you can usee their FOX or SmartStix I/O expansion (8 or 12 pt analog in, RTD).
I'd read the specs on scan time and such prior to pulling the trigger though (I don't think it'll be an issue but it is your project).
 
Wow then maybe I am wrong. Cheap to me is comparing Omron to Automation Direct. But Even those folks do not have a cheap 16 zone input device for thermocouples. I do not understand why it so expensive for this when 8 input A/D modules are cheap. Surley there must be some PLC dedicated to PID/Thermocouple zones.
 
I cannot use RTD's I have to use j or k thermocouples is this a issue? If there is no commercially avabile product or plc that can handle what I need to do. I can design and engineer a device to take in all these inputs and convert them to either a frequency or a voltage. But I do not want to do that because I am sure there is some PLC that can do this already. And without buying 4 racks of input modules.
 
Last edited:
maintenanceman38 said:
I cannot use RTD's I have to use j or k thermocouples is this a issue? If there is no commercially avabile product or plc that can handle what I need to do. I can design and engineer a device to take in all these inputs and convert them to either a frequency or a voltage. But I do not want to do that because I am sure there is some PLC that can do this already. And without buying 4 racks of input modules.
Click to expand...
You can set up the AIs for ThermoCouple, define which type or RTD as well as current ot voltage. I've used the onboard AIs.
The PDF is big (500K) so I cannot post here.
 
What is your hardware budget? One DL-05 can handle 4 loops for $298. That's $99 for the PLC and $199 for the four-channel thermocouple input card. You would need three DL-05s for your complete system. One C-More can talk to multiple PLCs, but you'll also need three RS232/485 converters at about $100 or less each. You can still come in under $1500.
 
From what I figured is this, PLC's= $400 I/O's= $800 HMI= $200 converters= $300 For a total of $1800. I thought I had to buy multipule HMI's I am still considering the Horner HMI as it looks promising but I would like to thank all you good pepole for your valuable input. my inital figure was 3000 witch was rejected untill an old controller overrode and blew up. nobody was hurt.
 
Last edited:
maintenanceman38 said:
From what I figured is this, PLC's= $400 I/O's= $800 HMI= $200 converters= $300 For a total of $1800. I thought I had to buy multipule HMI's I am still considering the Horner HMI as it looks promising but I would like to thank all you good pepole for your valuable input. my inital figure was 3000 witch was rejected untill an old controller overrode and blew up. nobody was hurt.
Click to expand...
What's your e-mail address?
Not sdure about pricing but the HMI/PLC combo with 2 AIs, 2AOs and digital in/outs is around 1100.00 my price.
Plus a module for the additional AIs another 500 or so you are looking at 1600.00 or more.
I will send you the brochure with the specs but you can check it out at the Horner site
www.heapg.com
 

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