RS-485 modules

[spider]

Hi all,

I have a question... Hom many RS-232 / RS-485 modules I can install in Unistream PLC. I must connect 12 modbus lines to PLC but in Hardware configuration menu in Unilogic I can install only 4 UA-02RSC-3 modules and I have only 9 RS-485 ports - 1 in CPU and 8 on modules).  How I can solve this? Investor wants poin-to-point connecton with every single sensor. 

 

[kratmel]

One of the possible solution - use  MOXA NPort 5650-16 or NPort 5630-16 with 16 RS485 to Ethernet convertor.

Or use 12 (or 12 minus unitream used port)   separated RS485 to Ethernet convertor. 

But you must test RS485 to Ethernet convertor setup for sensor used by investor.

Or use vision based solution from this

 

[Joe Tauser]

10 hours ago, spider said:

Investor wants poin-to-point connecton with every single sensor. 

You can't always get what you want.  RS485 is designed to be a multi-drop parallel network, not a star topology.  

It sounds like you've already empirically determined how many com modules you can hang off the back of a UniStream.

Let us know what kind of sensor you're using.  The obvious  alternative is an Ethernet connection of some kind.  

If that is not an option then kratmel has suggested the best solution with a multi-port serial server.

Joe T.

 

[spider]

Hi all,

Thank you for the answers. I must connect to PLC 8 valves, one 24V power supply and three flow meters. Every of them have RS-485 modbus communication ports. I wanted connect valves in one line but owner of this instalation don't want that solution. Now I have two solutions: 

1. I will use  MOXA NPort 5650-16 or NPort 5630-16 with 16 RS485 to Ethernet convertor
2. I will try to find modbus RTU to modbus TCP converter and connect all devices to ethernet switch.

I will ask owner with of those solution he wants

Kriss