Serial Communication with PLC

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Thread Starter

BJohn

I have an application where i need to connect about 50 number of power supply units to a PLC system. The PLC shall be responsible for monitoring the parameters of the power supply and generating setpoints for the power supply units. The problem here is the communication protocol for the power supplies is not a standard industry protocol. Power supply units communicate over propritery protocol which shall be required to be programmed in the PLC. Could some one guide which PLC would support developing propritery protocol.
 
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Steve Bailey

This is a typical application for a BASIC language module in the PLC. These modules can communicate with the PLC CPU via the backplane and also have one or more serial ports for communications with external devices.

Your BASIC program takes care of passing data between the PLC and the module and also controls communications with the power supplies via the serial port. This assumes that the manufacturer of the power supplies publishes the details of their protocol.

Check with your supplier to see which models of your favorite brand of PLC support BASIC modules.

Feel free to contact me off-list. I've done this sort of thing before.
 
Omron CS1 and CJ1 can have a comms card plugged into the CPU. This card can then be programmed with Omron Cx-Protocol software. It is pretty simple to use once you examine the samples.
 
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Yosef Feigenbaum

Hello BJohn,
Many PLC manufacturers have ASCII/BASIC modules designed to do what you want to do here.

You will have to pay attention to the power-supply communication connection (RS-232 vs. RS-485). If the power-supply is not addressable you will have to purchace an addressable interface module (there are many short haul MODEMS that have this feature). Note that an RS-485 network will be limited to 31 power-supplies (1 station is required for the BASIC module) which means that you should purchase a BASIC module with 2 programmable ports.

All that's left is to write the protocol. That's a bit too extensive to discuss here.

Feel free to contact me if you need more information.

Good Luck,
(8{)} ( .)

[email protected]
 
Omron CS1 and CJ1 can have a comms card plugged into the CPU. This card can then be programmed with Omron Cx-Protocol software. It is pretty simple to use once you examine the samples.
 
You can use Canadian Control Microsystems RTU/PLCs. You can program the protocol using c/c++ if you have the protocol details. You'll also have the RTU functionality like data logging, remote programming etc. Check www.controlmicrosystems.com
 
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BoB wrote:
> Omron CS1 and CJ1 can have a comms card plugged into the CPU. This card can then be programmed with Omron Cx-Protocol software. It is pretty simple to use once you examine the samples.<

I have written many protocols for the Omron PLCs that support protocol macro. It is a very elegant solution to this problem. Very high power data comms and error handling with basically ZERO ladder logic. V.nice. I have used it with: bar code readers, magnetic card readers, radar gun, electronic scale heads... Once you get the hang of it, it is waaaay simple. Need some help, email me.
[email protected]

Cheers!
 
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Joe Jansen/TECH/HQ/KEMET/US

I would recommend an Omron, probably a CJ1 or CS1. I am using a CJ1 with a SCU41 serial communication card. The serial card has 2 ports, and allows you to define and write custom protocols, and then embed the protocol into the card. I am doing this on a current project using lambda power supplies. The power supply uses it's own command set that runs over RS-232 or RS485. The card supports both.

If you like, I can give you more info. Contact me at [email protected] and ask.

As an additional benefit over the AB and BASIC module approach, the CJ1 and SCU is significantly less expensive than the SLC and BASIC module, plus is designed specifically for communications, instead of being a general purpose co-processor. Having worked with both now, there is really no comparison in comm capability. the Omron is orders of magnitude better when it comes to serial comms.

--Joe Jansen
 
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Orlando Charria

The T100 series PLC can be programmed in both Ladder and Basic. It includes three comm ports and you can add any propritary protocol.

Please feel free to contact me if you need more info about this low cost solution.

Orlando Charria
[email protected]
 
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Byron Sanders

Greetings...

I'm tasked with restoring a GE-9030 system with a PCM-301 that attaches to a bar code scanner. I original programmer can't remember how he did it. I have his old code, I'm struggling with the PCM configuration. I have three laptops for this: One with Proficy for the code, One with LM90 with PCOP built in for the PCM, one with Hyperterminal to see the Serial code from the bar scanner.

BOTTOM LINE, how to use a serial bar code scanner with a PCM, again I have the PGM file, it is the CONFIG that is driving us nuts.

Thanks for any tips.
Byron: byron.sanders [at] cstservices [dot] net

> This is a typical application for a BASIC language module in the PLC. These modules can communicate with the PLC CPU
> via the backplane and also have one or more serial ports for communications with external devices.

> Your BASIC program takes care of passing data between the PLC and the module and also controls communications with the
> power supplies via the serial port. This assumes that the manufacturer of the power supplies publishes the details of
> their protocol.
 
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