I have two devices which both implement modbus RTU master.

can I buy a "postbox" gateway to sit between them, so they can communicate?

 

You can use the MARC Omnii-Comm:

http://www.miille.com/din266-p00.pdf

for this type of application. Conceptually, you just define two blocks of holding registers A and B. Master #1 reads from A and writes to B and Master #2 reads from B and writes to A

Jerry Miille

 

Hi dexdyne,

HMS has a gateway that will fit your application, connecting two Modbus RTU masters.

For more detailed information go to:

http://www.hms.se/support/support.asp?PID=234&ProdType=AnybusX-gateway

or send me an email, support [at] hms.se

//Patrick L

 

ICC also sells such a gateway, which has multiple ports (2X RS-485 and 1X RS-232) that can simultaneously be configured various drivers (2X Modbus RTU slave, for example). You can find more out here:
http://iccdesigns.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=ICC&Product_Code=xltr200

Regards,
Darrin Hansen