I would appreciate if any one could give me some suggestion on the below described topic:

Topic:
I have Allen Bradely Controllogix LM5555 CPU and S7 300 PLC. S7 300 PLC is meant for a specific job i.e for load shedding. AB PLC has got all the data required for load shedding program. I need to send these data from AB PLC to Siemens PLC and the data needs to sent at a very fast rate i.e every 200 millisecs. I would like communicate on ethernet and propose to use AB ethernet card 1756-ENBT and Siemens CP343-IT ethernet card on TCP-IP protocol. I understand that though both the cards adhere to TCP-IP protocols there is a change in the application layer. Is this true. If yes is there a solution for this communication with out compromising on speed. Eagerly waiting for your suggestions. Other solutions with out compromising on speed is also welcome.

 

I think you are out of luck. AB and Siemens are competitors and not about to allow you to communicate between their PLCs. The TCP-IP protocol is the message transport level and the content of the message is specific to each manufacture.

Also your 200 millisecs rate is not very realistic, especially if you are doing any other communications.

My advice is the get rid of the Siemens and use some form of remote IO from the AB. The remote IO is dedicated to the acquisition of IO data and is not encumbered by other traffic. Any program in the Siemens can be written in the AB.

 

Pehaps you could use Profibus to Ethernet gateway, ... try products from Prosoft,

"http://www.prolinxgateways.com/products/4204.html":http://www.prolinxgateways.com/products/4204.html

Don't know what data transfer rates you will be able to achive, .. but their tech support should be able to help.

 

Use Profibus DP rather than Ethernet. Buy a Control Logix Profibus module part number SST-PFB-CLX from SST ( "www.mysst.com":http://www.mysst.com ). I believe it can act only as a master, but if memory serves the S7-300 can act as a slave as long as you're not already using the port as a master for remote I/O.

 

Hello;
There are ways to set--up communications with different brands of PLCs, but protocols have to correspond; unfortunately, you cannot use the different flavours of TCP/IP to talk between Siemens and Rockwell.
One other possibility is ProfibusDP. SST ( "www.mysst.com":http://www.mysst.com ) makes a Profibus scanner (master device) for ControlLogix. Using this module you can setup the S7300 as a DP slave (directly on the integrated DP interface, if available, or through a CP3425 Profibus comm. processor) and easily establish a link between the PLCs. On ProfibusDP you can exchange up to 256 words of data at 12 MBaud (up to 100 m; longer distances bring speed down). Your update cycle should be aroud 10 ms for a network of only 2 nodes, which is well within your specs.

Hope this helps,
Daniel Chartier

 

You're certainly out of luck with regard to TCP/IP. TCP/IP is the transport / data link layer. I don't know of any two competitive PLC vendors that support the other's proprietary TCP/IP application layer.

The closest to a "universal" protocol is Modbus RTU. An AB third party card for Modbus RTU (serial, not ethernet) is available, but I'm don't know about a similar card for Siemens.

Suggest you investigate a Modbus TCP/IP module for both PLCs.

Drake Fink

 

Both brands of PLC will talk Modbus.
set up comms to transfer data from register to register.
Use Master/slave with AB as master.
Use RS485 comms protocols.
Data transfer rate will depend upon amount of data being sent.

Regards

 

Your best bet is to check out what ProSoft has. They've got all kinds of odd-ball gateways.

Go to internet site:
"www.prolinxgateways.com":http://www.prolinxgateways.com

Good Luck

(8{)} ( .)

 

You will not get from A to B with Ethernet without something in the middle.

Try a gateway for PROFIBUS-DP such as ProLinx instead. I have not tried it, but I hear it works.

RA