Why status is change every time after execution of VI??

[AnkitRamani]

Hello,

I am not much familiar with Modbus communication,

I got one problem regarding to Modbus that when ever run my vi then after execution the status of DO3 is always changed and jump to the Alarm mode.

In attachment I have attached my screen shots you will get more clear Idea about my problem.

In LHS there is software window and before connection that software with instrument normally I set my DO3 at status mode but when I run my vi in order to check the supply voltage and after execution when I again connect that software then DO3 status always change and its come to Alarm mode.

Can you tell me that why its happen so??

and what kind of changes I have to do in order to avoid this problem....

Thank you  very much.

[AnkitRamani]

ok this problem is solve now that i have to make read holding register instead of write...

but still I am confuse about the mesurment of voltage generally i have to set like 

1) when (Do3 and datalogger switch both are closed) wired is connected with DO3 and relay on data logger is closed then its shoud show me voltage less then 2V,

2)DO3 is open and datalogger is connected then voltage shoud be near to V+ (12v in my case)

3)both are open then output shoud be 0V

4)datalogger is open and DO3 is closed then voltage shoud be V+

and in above four case i have problem in 1st case only...other 3 are working OK

will you please guide me that is ther any change I have to do in data logger and what king of settign I have to to in order to get desired Output.

I am not much familier with Data logger,i have read datasheet regarding to this and i am using Agilent Data logger 34970A.

Thank you very much...