Hi everyone,

I have a Schneider TM262L10MESE8T PLC and two Schneider TM241CE24T/U PLCs controlling five HSS86 stepper drives (2-phase Hybrid Stepper Servo Drivers). The motors are running fine, and everything works except for the PEND and ALM outputs of the drives. I need help, please.

According to the user manual, each drive has PEND- and PEND+ outputs, which are open-collector (OC) outputs. When closed, they indicate that the drive has finished moving to the desired position; when in open circuit, they indicate that the position is not yet finished. The ALM- and ALM+ outputs are supposed to function in the same way: if there is an alarm signal, the output is closed; if there is no alarm signal, it is in open circuit. The manual states that this feature is factory-enabled, but it is not working for me.

I have wired the outputs to my PLC as indicated in the manual, but I am unable to receive any input or detect a change of state from the drive outputs. Even when I activate the alarm by unplugging the encoder cables from the drive, the red LED on the drive turns on, indicating an alarm as per the manual, but I see no change in the output.

I have conducted some tests and measured the voltage at the outputs: PEND- and PEND+ consistently show 8.93 Vdc, with no variation whether the motor is stationary, jogging, or performing absolute movements. For the ALM- and ALM+ outputs, I consistently measure 8.95 Vdc, with no change even when I trigger the alarm and observe the red LED on the drive flashing. One of the drives does not output any voltage at all, and when I perform continuity tests, I detect no change, consistently reading 1.734 k?.

Has anyone else encountered this issue? Is there a specific way to wire these outputs? Am I missing something? Do I need to wire resistances or relays, if so how should I do it? I have seen videos of others using the same drives, where they connect the outputs as per the manual, directly to the PLC and their controllers detect the signals perfectly. Is there something else I need to do?

I have attached the user manual of the drive. I would greatly appreciate any guidance that can be provided.