I have two(2)slave and one RTU port, how can I connect? both slave RS 485 HD

 

Refer some sites related to modbus

 

Rs-485 is a multidrop interface so devices can be daisy chained together - each having a unique modbus address. You may also need to terminate each end device with a 120 ohm resistor.

 

If I understand you correctly, you have one RS232 port and want to communicate to two Modbus Slaves on RS485. If this is the case, you need a RS232 to RS485 converter. There are a number of brands to choose from.

HMS has a configurable gateway, see: http://www.anybus.com/eng/support/support.asp?PID=317&ProductType=Anybus Communicator

Best regards,

Pat
[email protected]

 

If your "one RTU" port is on a PC you can connect the slaves with SeeThru ($50) at http://www.tractrola.com

 

Why use the 120 ohm resistor? How do I need to connect?