Modbus Using RS-485, CPU 140 434 12A Quantum

tabrez

Member
Join Date
Sep 2004
Location
aurangabad
Posts
27
Hi Every one
1) I am using Quantum CPU 140 434 12A, Which has got two modbus comm ports,with XXMIT EFB and RS-232, i successfully communicate to the modbus device from modbus comm 1,But it is not working with the modbus comm port 2 even if i chaged port No. in the XXMIT EFB.

2)i Believe that these modbus comm ports can be used with both electrical media that is RS-232 and RS-485,as in the XXMIT instruction's command register BIT No.3 if i make it to 1 then the mode is RS-485 otherwise RS-232 default 0 (Zero) in that bit.
So i tried it using RS-485 with command register chaged to 1 in the Bit No. 3,but unfortunately it is not working at all and giving an error in the status register 129, offcourse the slave device i m using supports RS-485 MODBUS.
 
The native ports on the Quantum are RS232 only. Quantum supports the XXMIT command only on Port 1.

The options in the XXMIT command are for different processor families.
 

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