How to Choose a Controller – Part 4

Digital communications
There are six different types of digital communications.
Serial RS 232
Serial RS 485
Serial RS 422

The amount of instruments connected to the computer and the protocol of the instruments will determine the type of digital communications you select. The RS-232 communication port can only be used with one controller. If you are using more than one controller you need to specify One of the other types. The RS 485 and RS 422 communication protocols are similar in that they are either a two wire or a four wire twisted pair that starts at one controller and daisy chains to the last controller. Typically a Eurotherm controller will use Modbus protocol.

A couple of the New Eurotherm Controllers use Ethernet. The ethernet uses modbus over TCpIP and is wired via a switch. Please review other videos for specific instruments on how to wire any of these protocols. The devicenet and Profibus communications allow you to directly connect toeither an Allen Bradley PLC via Devicenet or a Siemens PLC vis Profibus. These protocols need special cards in the plc to communicate. If you have any questions about any of these please call us.

Ramp soak
Some controllers, have what we call a ramp soak profile. This option gives you the ability to ramp and dwell or soak at temperature over a course of time. Options include multiple recipes and event outputs. Depending on your process you may require recipes or events. We suggest that you contact us directly when specifying a ramp soak profile. We have several controllers to do this and depending upon your application we would determine what model you should use.


Overview of the communication options available, and a look at the ramp / soak feature.


communications, RS232, RS485, RS422, serial, ramp, soak