Hello
Im having issues reading and writing to a Digital IO port, in that it's taking a long time to accomplish my task. (it works, its just really really slow)
what im doing is reading and writing to an EEPROM chip. it has a read-only CLOCK line, and a read/write DATA line.
the clock line is controlled by Port1/Line6, the data line is
Port1/Line7. this is a permanent PCB connection and will not be an
easy task to change.
currently I do the following routine to write or read the port:
1) DAQmxCreateTask
2) DAQmxCreateDOChan
3) DAQmxStartTask
4) DAQmxWriteDigitalU32 (or DAQmxReadDigitalU32)
5) DAQmxStopTask
6) DAQmxCLearTask
but since the EEPROM requires back-and-forth reads and writes, bit for bit, im having to do the following just to read a single byte
write(clock line) - read(data line) - write(clock line) - write(clock
line) - read(data line) - write(clock line) - write(clock line) -
read(data line) - write(clock line) - write(clock line) - read(data
line) - write(clock line) - write(clock line) - read(data line) -
write(clock line) - write(clock line) - read(data line) - write(clock
line) - write(clock line) - read(data line) - write(clock line) -
write(clock line) - read(data line) - write(clock line)
and thats just one byte.
so im having to create, start, write, stop, and
clear tasks every time i switch between reading and writing ... which slows my throughput down a lot, since it seems to take about 25ms to create, start, and write a digital channel.
I'd appreciate any suggestions. I'm prepared to throw out my current method in favor of something better.
Thanks
(btw: WinXP, NI-DAQmx 6251, LabWindowsCVI)
