Digital Output
The DAQM907A module has two non-isolated 8-bit input/output ports, which you can use for outputting
digital patterns. You can combine the two ports to output a 16-bit word. A simplified diagram of a single
output bit is shown below:
l Each output bit is capable of directly driving up to 10 TTL loads (less than 1 mA). The buffer for
each port is used to drive a high output from the internal +5 V supply through the diode. The
drive is rated at +2.4 V minimum at 1 mA.
l Each output bit is also can active sink, capable of sinking up to 400 mA from the external
power supply. The FET is used to sink currents and has a nominal "on" resistance of 0.2 Ω.
l For non-TTL logic you must provide an external pull-up. A description of the pull-up cal-
culation is given on the following section.
l If used with an external power supply and pull-up, the external supply must be greater than +5
VDC and less than +42 VDC.
4Measurement Tutorials
224 Keysight DAQ970A User's Guide