using 6534 card, I am generating 8 bit data pattern using burst mode protocol. Same data i am acquiring using another 6534 card. If I keep no. of scans other than 256, I am missing last few data

[Nirmal_Sharma]

using 6534 card, I am generating different 8 bit data patterns continuously using burst mode protocol. Same data i am acquiring using another 6534 card using burst mode protocol. I am connecting REQ signal of Ist 6534 card to the ACK line of IInd 6534 card. Similarly I am connecting ACK line of Ist 6534 card to REQ signal of IInd 6534 card. Also I am connecting PCLK1 of Ist card to PCLK1 line of another card. I am operating two vis, one for writing & another for reading same pattern using handshaking burst mode protocols. Now if I keep no. of scans other than 256 in the write vi,
when I am acquring data by read vi, I am missing last few data. I have tried by varying all other possible parameters such as frequency, delay etc. but i am not able to read all the data correctly or some data are missed.

Pl. help

Nirmal Sharma
Engineer
Autotec Systems Pvt. Ltd.
Bangalore, INDIA

[JustinBritten]

Nirmal,

Most likely your problem is due to the fact that the 6534 transfers data in blocks of 32 bytes when using DMA. If you are not reading in multiples of 32 bytes when using DMA transfers then you could have up to 31 bytes of data available in the internal device FIFO. You can use interrupt driven transfers if you need to retrieve data immediately as it is acquired. Please see the 653X User Manual, page 2-10, for more information.

653X User Manual
http://digital.ni.com/manuals.nsf/websearch/EDE443F5C700373A862569B90072D26F?OpenDocument&node=4575_US

Regards,
Justin Britten

Applications Engineer
National Instruments

[Nirmal_Sharma]

Thanks Justin,
I tried with the above method, i am getting all the bytes successfully. Again redifining the problem, in real time application, I am getting 16 bit digital data every 5 microsecond before which I get a DVALID signal which is active low. DVALID signifies the presence of this 16 bit data. Now I am producing some different pattern using the internal clock option using 6534 card. I am connecting REQ signal from this 6534 card to REQ line of IInd 6534 card. In IInd card I am defining I/O connector option in the Start vi which means that whenever REQ signal goes low, it will read data pattern. But adopting this method, when I run write data vi, my pc reboots. Also I am missing certain bytes in between.

Pl. help.

Regards,
Nirmal Sharma

Enginner
Autotec Systems Pvt. Ltd.
Bangalore INDIA