How to Communicate Servo Drives with PLC

The SLC 5/03 already has a DH485 port, so you wouldn't need an external device, but if you plan to expand your network or use an operator interface, you might want to try this.

About the logic, your programmer must be able to work with AB comm. instrutions or study them while the system is being installed.

Regards

First thing in mind "compatibility". Consult or read manuals. See system architecture.

Hi;

Great brochure, but I think he wants to keep all the old drives, wich are RS485; probably due to budget limitations; otherwise, it would be a very interesting project, to add an ethernet module to his PLC and start from "ground zero".

1) Do I understand it properly that you intend to remove the PC and its DOS program and the existing communications module and replace them with a PLC which will be the master controller of all the drives?

2) Do you possess full documentation on the existing drive protocol so that someone can replicate the communications scheme ?

3) RS-485 is a physical transport layer for digital communication, a mule. Mules carry data. Mules do not pack or unpack data, nor interpret data. RS-485 is not a protocol (a set of communications rules).

Your proposed network will involve some communications protocol. Not all communications protocols went to kindergarten to learn to play well with others and most do not.

Allen Bradley's DH-485 might run on the physical RS-485 transport layer, but it is a full scale network with its own protocol, including token passing.

http://www.ab.com/en/epub/catalogs/12762/2181376/214372/1535907/3404063/index.html

Note the comment, "With RSLinx software installed on a PC, communication with other nodes on the network is possible." I suspect 'other nodes' is A-B talk for devices with protocols who don't play well with DH-485 because they aren't DH-485.

DH-485 is NOT the same as a programmable RS-485 port.

This is not unlike the situation with Profibus DP. The Profibus PA protocol uses RS-485, but no Profibus DP port can be used for anything but Profibus PA.

Unless your drives already talk the DH-485 network protocol, you will need some other comm module to accomplish this task.

4) Prosoft is a 3rd party supplier (an A-B partner) of communications modules for SLC platforms with various hardware ports (RS-485, for example) and protocols, including custom programmability.

Hi Iris,

We have several modules which may help you communicate to your Servo motors. Depending on which ports you have available and what protocol the Servo motors use. Here's a few possiblities

USB to RS-485 http://www.icpdas-usa.com/products.php?PID=3809

Ethernet IP to Modbus RTU (RS-485) http://www.icpdas-usa.com/products.php?PID=3811