How to split one modbus serial output port into two?

[Roger CHAN]

Hi all,

Current Situation 

My company has a instrument measuring emission in flue gas. The instrument has only one serial port for "modbus" output. The serial port is being used to sending the data collected by the instrument to our DCS.

My Question

I have a separate data acquisition computer which is also able to collect data over serial modbus. Is it possible to split the existing serial modbus output port into two so that both the DCS and my data acqusition computer can collect data from the instrument at the same time? If yes, what software and hardware do I need? One more point, high reliability is required for both data collection processes - to the DCS and to the data acquisition computer.

Thanks and regards,

Roger 

[pflores]

What serial protocol are you using? RS-232 or RS-485?

If it is 485, then it is a multidrop bus, so you can just hook up both receivers to the transmitter via a RS-485 hub. If it uses the 232 protocol, then this would not work as only one device can receive data at any given time, so you could set one node up to repeat the signal to the second hub or use LabVIEW Shared Variables.

A Quick Comparison of RS-232, RS-422, and RS-485 Serial Communication Interfaces

Regards,