example "NI 9870 Continuous Serial Read On-Demand Write.lvproj " doesn't work

[Tatsuya.F]

Hello,

I'm using NI-9870 and cRIO-9074 for serial communication with a outer module (Mesytec MRC-1).

I got the example "NI 9870 Continuous Serial Read On-Demand Write.lvproj " and managed run the programs.

I didn't change the example anywhere.

However, when I tried to write commands in order to read some status of MRC-1,

the response was the same as what I send.

This is strange.

For example, when I write "RE 0 0 4" to the module, I get "RE 0 0 4".

The correct response should  be "RE 0 0 4 0".

When I connected to the MRC-1 directly from a PC by PUTTY, I got the correct response "RE 0 0 4 0".

Could you help me and tell the reason why I can't get the correct response?

[W.Muhammad]

Hello Tatsuya.F

This Muhammad Waqas from National Isntruments Japan.
I will be assisting you with you question.

1)How about the Baud rate you are using?
2)Can you please test by writing "RE 0 0 4 " with space after 4. 

3)Are you sure you dont need to use EOL letter.

4) Please check for some other commands of RMC too.

Please confirm the above.

regards,

[Tatsuya.F]

Hi,

Thanks for your advise.

I changed some program and made the length of time out longer, then it worked !

However, I have another problem.

When I send the command "re 0 0 4", the response on the "Port 2" is bellow,

re 0 0 4

RE 0 0 4 0

mrc-1>

(The number "0" on the last word at "RE 0 0 4 0" is the result which I need.)

Response on the Array 2 is bellow,(which is the same as the command I send.)

re 0 0 4

However, when I send the same command "re 0 0 4" many times,

message on the Array 2 suddenly change to " 0 4".

This change always happens after sending the same command 18 times.

Could someone help me, please ?

Tatsuya

[W.Muhammad]

Tatsuya.F

It looks like that program being used is not reading the whole data available from the port.

Main reason can be , Read functions dont have enough time for execution.

I wonder what happen if you increase your time-wait function(from 10 mSec to somewhat 100m sec)

being used in your Host VI.

regards,