controller's communicution

Hi Everybody,
I am a passive participant of the Forum for about a year. It's very helpful and useful for me as I have been programming PLC for some years.
Now I need HELP. My problem is:
A Controller ( Omron CQM-1H ) must get information(frequency,working current, error information,etc.)from 28 engine drivers ( Omron type)
and,if necessary,change control frequency for some drivers.
I don't know how to do it,
I even have no idea what I should start with as I have never worked with communication.
I am going to use Omron PLC but if any other controller is better in this situation,I am ready to use it.
Any ideas, advice, suggestions and recommendations are accaptable.
Thanks,
Evgeny

Probably your best bet is some form of field bus.
I've completed a similar job using Siemens + 3rd party drives on Profibus.
Some Omrons can also do profibus, but not all.
I think Omron supports device net quite well, so that may be able to give you what you need.

Hope this helps,

Doug

A Controller ( Omron CQM-1H ) must get information(frequency,working current, error information,etc.)from 28 engine drivers ( Omron type)

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The CQM1H primarily masters other devices through serial communications. It is true that Profibus and DeviceNet are available for the CQM1H, but only as a slave device.
Can you describe the Omron "engine drivers" as to model numbers and amount or frequency of data?

I am going to use Omron inverter - 3G3MV or YASKAWA VS-606V7

I am going to use Omron inverter - 3G3MV or YASKAWA VS-606V7

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The Omron 3G3MV and the Yaskawa VS-6-6V7 are the essentially the same product and use Modbus communnications. There are several ways to use Modbus with the CQM1H PLC.

1. Through the use of the ladder TXD and RXD commands
This method is the least expensive because all CQM1H CPUs have these commands and also have a built-in RS232 port. Since you will be using multiple drives (inverters), you will have to convert the port with an RS232 to RS422 convertor. Omron's NT-AL001 is a good solution, but other third party adapters will work. This method is also the more complex, because all commands to the drives must be kept as ASCII strings in multiple DMs (Data Memeories). Also, the Modbus specification demands the calculation of a CRC16 error checking routine which can be done in ladder, but is very complex. See your Omron representative in Israel and ask him to contact Omron Europe for ladder examples.

2. Through the use of Protocol Macro communication board CQM1H-SCB41
This method involves the purchase of an additional board which slides into the CPU and provides an RS232 port and a a RS422/485 port in addition to the built-in RS232 CPU port. The advantage is two-fold. First, the port is already RS422/485 and does not need to be converted. Secondly, the communication board has the ability to store up to a thousand pre-determined Modbus commands which are called by a single ladder command. The 3G33MV command set has already been written for this board and can be loaded with a special loader program avilable in the U.S. See your Omron representative in Israel and ask him to contact Omron North America for details. I will attach the documentation for the 3G3MV protocol macro to this post.

A Controller ( Omron CQM-1H ) must get information(frequency,working current, error information,etc.)from 28 engine drivers ( Omron type)

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If you choose the Protocol Macro method, there is a single command which will return you all of the above parameters.

and,if necessary,change control frequency for some drivers.

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The commands are available in the Protocol Macro for changing frequency references. If you are trying to change many frequency references at the same time, remember that Modbus is a master-slave relationship and only one drive at a time can be changed. If you are continually changinging frequencies, you may want to consider analog out from the CQM1H to set those frequency references. If all you are doing is adjusting the frequency reference occasionally and you do not need to synchronize drives, then the Modbus method is OK.

beerchug
Thank you evrybody for help.
Jay, thank you. Your recomendations seem to have worked.