RS422 to RS485 Conversion Help

DwSoFt · May 3, 2016

Ok so here are the Details of what i need to do.

I have 3 Proprietary Pump Speed Controllers that Talk RS422 4wire, and Modbus RTU. The controller is a Trido (I have their manual and i have talked to tech support). And I have 1 Fisher Roc FB107 with an Open RS485 port and it supports Modbus RTU Master.

I need to connect the 3 pumps with the Master, so im looking for industrial converters that would allow these 3 to talk to that 1 master port.

Any help would be Apreciated, Just dont know what converter to go with. Thanks

jrwb4gbm · May 3, 2016

Try these people, they have a large line of converters, maybe you can find something that will work for you.
http://www.bb-elec.com/

Firejo · May 3, 2016

This is a RS-422/RS-485 repeater but it has a feature that will convert RS-422 to RS-485 and vice versa.
https://www.blackbox.com/store/us/Detail.aspx/RS-422-RS-485-Industrial-DIN-Rail-Repeater/ICD107A

Bullzi · May 3, 2016

I will second B&B Electronics. I have used their converters for years.

Just wondering, many of the devices that I use in the Oil Industry have a 4 wire 422/485 port but I have made them work 2 wire by jumping the + terminals and - terminals to each other. Are you sure you can't do the same with your devices?

DwSoFt · May 4, 2016

I have used their converters before with success. I will get a quote on them yet.

I don't know Bullzi . on the Controller the port it says rs422/485 but in the manual it not only says it doesn't currently. support 485 only 422 4 wire. it also says it.must be point to point, not multidrop. makes things more difficult.

Bullzi · May 5, 2016

Wow I am really surprised that they would offer a product that did not allow multidrop!!

That being the case I guess you are stuck with a converter.

Firejo · May 6, 2016

I have used their converters before with success. I will get a quote on them yet.

DwSoFt said:
I don't know Bullzi . on the Controller the port it says rs422/485 but in the manual it not only says it doesn't currently. support 485 only 422 4 wire. it also says it.must be point to point, not multidrop. makes things more difficult.

RS422 it technically meant to be a point to point connection however so is RS232 but there are all kinds of RS323 devices that operate half duplex. The thing to find out is that when the port is configured as an RS422 port (I.E. point to point) do you still have multipoint options (can you message to more than one address)? That’s not a guarantee that it will work but it might.

jdbrandt · May 6, 2016

DwSoFt said:
Ok so here are the Details of what i need to do.

I have 3 Proprietary Pump Speed Controllers that Talk RS422 4wire, and Modbus RTU. The controller is a Trido (I have their manual and i have talked to tech support). And I have 1 Fisher Roc FB107 with an Open RS485 port and it supports Modbus RTU Master.

I need to connect the 3 pumps with the Master, so im looking for industrial converters that would allow these 3 to talk to that 1 master port.

Any help would be Apreciated, Just dont know what converter to go with. Thanks

+++ for B&B, along with others.
I had a MODBUS link with oddball slaves problem a few years ago which was driving me crazy. Everything was hooked up right, but it wouldn't communicate. Finally, some kind tech support guy suggested that perhaps things needed to be isolated. So, I went out and bought an isolation device, and all was well with the world. I won't even try MODBUS anymore without an isolation device of some kind.

RS422 to RS485 Conversion Help

DwSoFt

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jrwb4gbm

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Firejo

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Bullzi

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DwSoFt

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Bullzi

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Firejo

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jdbrandt

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