PowerFlex 40D Variable Frequency Drive (RS485 communication wiring)

[Bogdan.Vlad 0]

Hello!

I have a PowerFlex 40D Variable Frequency Drive and I want to control it with Arduino. I'm really confuse of where to connect the two wires (+ and -) of the TTL to RS485 module to the VFD terminals. Here is the manual of the VFD:

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/22d-um001_-en-e.pdf

The information about RS485 wiring can be fount at page 149.

Some help with this?

[kaiser_will 65]

http://www.brainboxes.com/files/catalog/product/US/US-324/img/US-324_RS-422_485_Pinout.jpg

[NevergoldMel 38]

You need a converter to go from TTL to rs485. There's a voltage difference that could potential cause damage to cheaper equipment.

This is specifically made for what you're doing.

uxcell 5V MAX485/RS485 Module TTL to RS-485

[Bogdan.Vlad 0]

I use exactly that converter for my project. I'm a newbie with industrial devices communication but I have experience with Arduino. I know is not the best approach to directly try to make what I try to make but I have to develop a robot prototype only by myself and I have to deal with everything (electrical, mechanical, programming...).

My problem is that I don't know for sure how to wire the TTL to RS485 module to the VFD. In the manual from the attached link it doesn't give enough details. By the way, is there a possibility that I can put some kind of protection between TTL to RS485 module and VFD, like optocouplers for example?

[NevergoldMel 38]

It's on page 149

Note the text from page 150

Quote

Only pins 4 and 5 on the RJ45 plug should be wired. The other pins on the PowerFlex 40P RJ45 socket must not be connected because they contain power, etc. for other Rockwell Automation peripheral devices. Wiring terminations on the master controller will vary depending on the master controller used and “TxRxD+” and “TxRxD-” are shown for illustration purposes only. Refer to the master controller’s user manual for network terminations. Note that there is no standard for the “+” and “-” wires, and consequently Modbus device manufacturers interpret them differently. If you have problems with initially establishing communications, try swapping the two network wires at the master controller.

 

[Bogdan.Vlad 0]

Thank you for support! It's clear for me now. But just wondering, can I somehow put a protection between RS485 module and VFD, like optocouplers for example?

Edited 15 Dec 2017 by Bogdan.Vlad

[NevergoldMel 38]

It's based on voltage differential signaling so an optocouple would kill it. You could try a quarter amp fuse. 

[Bogdan.Vlad 0]

Thank you! I will do so.