LJTick DAC | LabJack


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lnadolski's picture


I have configured a LJTick DAC using VS, GND, FIO4 ad FIO5 on U3-HV. I am also using a PS12DC connected to DB15 connector to control some 24V signals and have two encoder signals connected to FIO6 and FIO7 which are configured as counters.

The LJTick DAC voltage works well, however whenever I set one of the DB15 signals high to control the connected PS12DC, I see very large counts on   FIO6 and FIO7. If I manually rotate the motor shaft connected to the encoder I see a pulse count as expected.

Are there limitations to how to configure a U3-HV using LJTickDAC on FIO4/5, using FIO6/7 as counters and having a PS12DC connected to the DB15?

Thank you in advance for your assistance.


LabJack Support
labjack support's picture
Sounds like whatever load

Sounds like whatever load switching you are doing via the PS12DC that is creating noise on or otherwise messing up your encoder signals, resulting in a bunch of counts on the counters.

Is there a particular reason you think the LJTDAC is related to the problem?  Seems like the problem is interaction between the PS12DC and the counter signals on FIO6 & FIO7.  Remove the LJTDAC and any related software commands and see if you still have the problem with the PS12DC-FIO6-FIO7.

Disconnect your loads from the PS12DC so you are just controlling the PS12DC but not actually switching any loads.  Does the problem go away?

Disconnect your wires to FIO6 and FIO7 and see if the counts go away when they are floating or when jumpered to GND.