Why Can't I Make Measurements With Either WE7141 Universal Counter or WE7261/WE7262 Digital I/O Module?
With either the WE7141 100 MHz universal counter module or the WE7261/WE7262 32-bit digital I/O module, if you are performing continuous measurements with more than three of the same modules you must set the sampling interval of each of those modules to 20 ms or higher.