VISA error code -1073807239

[DavidPhung]

Hi,

I am using NI-VISA 5.4 to communicate with Keithley SMU 2636B. On the PC, my application registers a callback to receive service requests from the meter. Once a service request is received, the application calls "ReadStatusByte()" from the MessageBasedSession object to get the status byte and processes it.

That logic works fine most of the time. However, the call to "ReadStatusByte()" fails intermittently with the below error message:

"The protocol specified is invalid.  VISA error code -1073807239 (0xBFFF0079), ErrorInvalidProtocol"

I would appreciate any help I can get on this issue.

Thank you,

[nyc_(is_out_of_here)]

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@DavidPhung wrote:

Hi,

I am using NI-VISA 5.4 to communicate with Keithley SMU 2636B. On the PC, my application registers a callback to receive service requests from the meter. Once a service request is received, the application calls "ReadStatusByte()" from the MessageBasedSession object to get the status byte and processes it.

That logic works fine most of the time. However, the call to "ReadStatusByte()" fails intermittently with the below error message:

"The protocol specified is invalid.  VISA error code -1073807239 (0xBFFF0079), ErrorInvalidProtocol"

I would appreciate any help I can get on this issue.

Thank you,

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Googling ----> http://www.ni.com/support/labview/visa/verr3.htm

[DavidPhung]

My application communicates with the meter through LAN, not serial. Moreover, the application open a VISA session only once at the beginning. So the solution does not seem applicable to us.

[Cavarval]

That error can be related to trying to send too much information at once using a single write command. Please check the following article:

http://digital.ni.com/public.nsf/allkb/22D4DC24C65123EE86256F12005BCCEE

This does not necessarily explain why the problem seems to be intermittent and the article mentions writing to the device, so I am not sure I will solve the problem in your case. However, since there is not much documentation about that specific error code, I believe it is worth trying. Iif the problem persists after turning "Send End Enable" off let me know and I will dig deeper to see if I can find something for you.

Screenshots from the error window and even the block diagram would be useful for further research.

Also, the fact that the communication goes through LAN does not necessarily mean it is not serial. Still, if you open the session just once at the beginning and close it at the end, it should not be that the session is already open.