I’m trying to understand the ground connections for the analog I/O:
Are the AG connections tied together? How?
On my UR3e, if I put an ohm meter between any 2 of the AG terminals, I read 4.5 ohms. Between any of the AG terminals and the GND terminal on the gray Power connector, I see 2.4 ohms.
Virtually no resistance (0.2 ohms) between the GND terminal and system ground/case.
Makes me wonder what effect this could have on input & output devices. The manual says to use the analog ground closest to the IO connection, as they “share a common mode filter”.
The reason I’m checking is that I’ve connected Honeywell model GM amplifier voltage outputs to my analog input. This is reading a load cell.
As part of the calibration of the load cell/amplifier system, I check the output voltage and zero it out, then adjust scaling to get the correct voltage and display values for a known load.
If I make those adjustments while only connected to a voltmeter, then hook the amplifier outputs to the UR analog inputs, I see a jump in the voltage and display - only about 1% of full scale, but that’s 20% or more of the range I’ll be using in practice.
At this point I’m just making sure to do my calibration with the connection in place to the robot, and am checking with Honeywell to get their thoughts.
However, I’d like to have a better understanding of how the grounds are connected in order to have an intelligent conversation with them.