nat 7210

[Rona]

we have a board using NAT7210 and a microcontroller.

when i perform read from the pc and i did not finish my data prcessing in the microcontroller the NAT do not wait for the data and the PC application returns on timeout.

is there a way to make the GPIB BUS wait until my data is ready?

thanks

Rona

[Collin M]

Rona, can you just increase the timeout in the application on the PC? If you are using NI-488 the timeout can be made very large.

[Dennis_Knutson]

And you can certainly do things better at the instrument end. When the data is available, you can have the instrument issue a service request. Then the controlling program can do a wait on SRQ and when tru, do the read.

[Rona]

hi

thanks for your answers but...

the problem is that this is that the labview driver need to be the same as  at other products we have. I need to find a way to send the labview device not ready or something semiliar so the pc driver will send read only when data is available....

thanks

Rona

[Collin M]

Rona,

Does the program running on the PC continuously try to read data from the device, even if there is no data available? Or does the program read data when the device has data to send, and the device is slow transmitting the data?

After reading your last post it seems that the first statement is true. If so, then Dennis' suggestion is the best implementation. The device can assert the SRQ signal to notify the host controller (PC) that it has data ready to send. The host (PC) should wait until it receives a service request (SRQ) from the device, serial poll the device, and then read data from the device.

Serial polling is similar to the way interrupts work in a PC. A device can assert SRQ at any time to notify the host of some change in state. The host receives one byte from the device during a serial poll. This byte indicates the reason the device asserted SRQ.

[Rona]

thank you all for the help.

Rona