Thanks for the reply.

Can you confirm the attached wiring scheme of 2 wire rs 422 ?

And I believe in configuration of ptp there is only two option

Rs 422 4 wire full duplex

Rs 485 2 wire half duplex

So for two wire mode/bus mode I must use rs 485?

I have tested it with RS 485 two wire and scenario is same as 422 4 wire mode. Please find the picture for the schematic I have followed.

RS 484 behaved same with one device switched on 
 I can give command TX and devices respond back RX without error and NDR = 1

But with two devices TX blinks but none of them responds in RS 484 mode. 

for more clarification, I used HyperTerminal at both ends

1. Hyperterminal at CP end[CP disconnected] and checking data: Two devices switch on = No data

 Individual device On = data available at hyper terminal

2. Hyper terminal with Loadcells and CP as master 

Situation is while both Loadcells are switched on command from CP cannot be detected by Loadcells or hyper terminal [ TX is blinking ] 

If both devices are off command from CP is available at HyperTerminal
If anyone of a device is ON, Hyper-terminal can monitor the reply data from slave as exactly as it is available to CP card.


With one device on  TX = Ok   RX = okie NDR = True & Error = None

With two Device in bus = TX okie  RX/NDR = 0  and still Error + None


Any thoughts? Resistors are connected well.