RS-485 vs Ethernet between two TRI PLC

[cch1955]

I have an application where I need to have communication between two Triangle PLC'S I need this to be very robust and the data rates will be low. The enviroment is outdoors or in a light industrial area. Possibly some RF around from devices in the facility. A couple of stepper drivers are also in this system.

I would like to use the Ethernet using non-shielded CAT5 or CAT6 cable so I could easily interface to PC'S The RS-485 looks to be very robust but not my first choice.

Based on many application of your products in many situations, which is a good choice?

[support]

If it is just between two PLCs and the distance is short (<100 m), and one of them is always a master and the other a slave then RS485 is an easy choice. Programming is easy and monitoring traffic between the two devices is quite simple during program debugging stage.

Ethernet is a better choice if both PLCs can be master or slave at the same time since Ethernet allows peer to peer communication.

If data rate is low using the lower baud rate of RS485 can be more robust against interference.

Severe electrical noise is always an enemy to proper communication. So if there is strong electromagenetic interference then steps must be taken to protect the communication wire from the source of interference.