Which products are affected?
ESP-SPAC-Pos
Template Positioner V2.2
What happens?
In case of high homing velocities the home position detected is shifted by some 1,000 increments compared to the home position marked by the TP signal.
When does the problem occur?
During homing when using a TP signal as home signal. The TP signal can be received from an external terminal (E4) or via X8 (zero pulse). Further conditions are an inverted motor mounting position (C3000 = 1) or different settings under code C3000 (motor mounting position) and C3001 (encoder mounting position), e.g. C3000 = 0 (non inverted motor mounting position) and C3001 = 1 (inverted encoder mounting position).
The current position is saved when detecting the TP signal edge. When processing the task this position is added to the distance which has been traversed in the meantime.
During this calculation the value must be inverted. Since this inversion is not considered in the positioner template V2.2 the deviation of the home position detected is twice the amount of the LastScan value compared to the hardware home position.
Possible diagnostics:
Carry out homing twice (once with a very low homing velocity and the second time with the max. possible homing velocity). If deviations which amount to some 1,000 increments can be detected these may have been caused by the restriction described before.
Homing is to be carried out with a velocity as low as possible.
Short-term measure:
The calculation is made in a template section which is not accessible for the user. As a result, the home position determination cannot be influenced.
Evaluation:
This function restriction has already been eliminated in the more recent versions of the positioner template. Compared with the actual poduction process homing procedures are usually executed quite rarely, e.g. once per day/shift. Therefore, a low homing velocity should be tolerable in general. Occurring deviations amount to a few 100 increments only.
