what is labview digital write-to-line logic high voltage?

[np 558]

i'm using a pci-6503 daq hardware and cb-50lp.I'm currently doing a project to interface a labview vi to a programmable chip(downloaded with a vhdl program),using the daq hardware.The chip must function according to the labview program.I'm using 2 digital write-to-lines and 6 digital read-from-lines to interface to the chip.
Problem:
the 6 digital read-from-lines are able to read from the chip,but the 2 digital write-to-lines are unable to reach a logic high of 5v.This means that the labview vi can only read and unable to write to the chip to function(only one way communication).In the daq wizard,when using the test panel to test the individual lines of port a,b and c,it is able to write a good
logic low and good logic high(5v),even when all the lines are being used altogther.But when the labview vi is being run, the write-to-line cannot write a good logic high,thus unable to interface completely with the chip.
Please advise.Urgent!



grays

[Tim_Ousley]

LabVIEW does not do anything different to the PCI-6503. NI-DAQ outputs the same 5V from MAX and LabVIEW. Are you sure the FPGA isn't driving 0V on the same line? You could test this by putting a small resistor between the FPGA and the DAQ card. See what the voltage is across the resistor.

Even at 2.5mA, the 6503 should output 3.7V.