<p>I have a non redundant system that communicates over ModBus RTU (RS232) to a redundant system. In order to make this nonredundant connection into a redundant connection, what I need to do. Has any body done this before. Can using an amplifier help and if yes what is the device name that can do such a job?</p>

<pre>

|------>RS232 interface
<------RS232-------->---
|
|------>RS232 interface
</pre>
<p>Many Thanks</p>

<p>Lala</p>

 

Have done it by converting from RS-232 to RS-485 and back. Check with B&B Electroncs ( "www.bb-elec.com":http://www.bb-elec.com ) for converters and a very nice set of application notes. The standby master system tri-states its RS485 unit usuall by lowering RTS.

 

Hi Lala

We have done this a number of times using the FS-B4010-01 multiple serial port communications bridge. "www.fieldserver.com":http://www.fieldserver.com The serial ports can be set up as a master or slave to form a port expander application.

Thanks,

Richard

 

I am not sure which of the following you are trying to do.

1) If you want two Modbus masters to share a serial communication link to one or more Modbus slaves then see the PLC09 Modbus port arbitrator at "www.calta.com":http://www.calta.com . ( This is not just an electrical problem if you want the two masters to poll at same time ).

2) If you are just trying to multidrop more that one modbus slave on an RS232 link then there are a few options. You can use 232-to-485 converters, line-drivers, leased-line modems, or splitters.

You can find some of these gadgets at "www.blackbox.com":http://www.calta.com or
"www.bb-elec.com":http://www.calta.com .

Jay Kirsch

 

Is your non-redundant system a Master or a Slave. If it is a Slave that needs to be connected to redundant Masters, then the Miille Applied Research Co. Multii-Port module will do this for you. Check out this module at "http://www.miille.com/din366-10p.pdf":http://www.miille.com/din366-10p.pdf

If the non-redundant system is a Master then you should probably rig up some sort of mechanical (relay) switch to select one network or the other.

Jerry Miille