DSQC355-analog board "jumping" signals

Robot Controller
1

hallo All,

I have next problem:
in a S4C+ controller, I am using a DSQC355 board. the board can handle maximum 4 analog inputs and 4 analog outputs.
I’m using 2 analog inputs. (voltage signals).

if I keep the signals stable, (measured with a multimeter on the wires of the signals, while not connected to the board and also while connected on the board), I can see on the teachpendant jumping the signals continiously in a range of 0.1 volt.
I was also logging the signals to make sure it is not only a “visulatisation problem”.
also in my logging I see a deviation of 0.1 voltage.

I was thinking that the can bus had somewhere a bad connection or was overloaded by a lot of cards that we are using in the robot. I prepared a bus cable with only one adress connector… the result was the same as before.

I have this problem now in 2 robots, in other robots with the same application, I have not this problem.

does somebody has any idea how to solve this?

thx,

bart

2

Hello,

Off the top of my head I would look at 2 things:
a) Grounding of the signals and the shielding of the signals going into the 355 board,
b) Check the EIO configuration and the definitions of the physical range and logical range, these can have the effect of amplifying the percieved noise on the signals.

Of course if the settings are the same as on the other robots, it may be more of a grounding/shielding problem.

Steve

3

Hello Steve,

thank you for your answer.

I have 2 signals, on one of theme I don’t use a rescaling, the other one is amplifying with factor 1.5

I understand that grounding and shielding can have such effects, but is there than any explenation, why if I measure the signals (on the analog board) I get a stable signal?

regards,

bart