HART protocol

[nisz]

i'm using labview 6i. i'm trying to create a program for communication with smart transmitters. i'm able to write to the transmitter using VISA write. but while using VISA read the error message is "time expired before operation completed". plz do giv me some ideas on how to solve this problem.

[nisz]

i'm using labview 6i. i'm trying to create a program for communication with smart transmitters. i'm able to write to the transmitter using VISA write. but while using VISA read the error message is "time expired before operation completed". plz do giv me some ideas on how to solve this problem.

[Mholt]

I don't know your skill level, so if this is below you please disregard.

The VISA read will return time out if you are telling it to receive more than is waiting to be received (example: the response is 12 bytes long and you wired a 13 to the byte count)... try using a property node to get the "Bytes at port" count and use this number directly wired to the read. Only read if there are more than zero bytes ready.... depending on the device you are communicating with you will likely have to wait before getting a response.

[nisz]

I don't know your skill level, so if this is below you please disregard.

The VISA read will return time out if you are telling it to receive more than is waiting to be received (example: the response is 12 bytes long and you wired a 13 to the byte count)... try using a property node to get the "Bytes at port" count and use this number directly wired to the read. Only read if there are more than zero bytes ready.... depending on the device you are communicating with you will likely have to wait before getting a response.

thanx for replyin.

i've already tried using bytes at serial port vi. but the number of bytes at serial port is zero. i even tried settin timeout to 5sec, still zero bytes at serial port. In visa config serial port vi my settings are 1200 baud, 1 stop bit, 8 bits, odd parity. also i'm able to write to the instrument i.e., when i send some command to change a parameter, i'm able to see the change in the display of the monitor. What should be the time delay between the command send by the master and time for the slave to reply.

waitin for ur valueble suggestions & ideas

[malef]

Please give us some more information about your setup:

- model of HART interface?

- type and model of transmitter/device you try to communnicate with?

- can you check wiring and communication by a handheld HART communicator?

- can you verify communication by sofware provided by manufacturer and HART modem?

Application Guide on www.hartcomm.org may help to understand HART comm.

Some more links:

http://www.romilly.co.uk/booklet.htm

http://www.analogservices.com/

http://www.cardiac.no/Download/HLLinkPRO_Datasheet.pdf

I am working with ready to run software from the manufacturers and not familiar with HART internals.

Just my :2cents:

Manfred

[nisz]

i'm using SMAR H1311 (HART modem) in comm1.

i'm tryin to communicate with pressure transmitters like rosemount, smar. The software provided with SMAR transmitter which is CONF301 works fine with rosemount and smar transmitter.

but the program i've created with labview 6i is able to write to the transmitter i.e., i'm able to change the units of pressure (from mbar to bar and back to mbar) but not able to read. Timeout expired before operation completed is the error message when tried to read from the transmitter.

tryin the same program with labview 7.1 will help or shud i go on with labview 6i?

thanx for the links u provided. i've already gone thru them.