ADLINK PCI-8154 - Manual (Page 82)

72 Operation Theory
4.3.5 Error clear signal
The ERC signal is an output from the motion controller. It tells
motor driver to clear the error counter. The error counter is
counted from the difference of command pulses and feedback
pulses. The feedback position will always have a delay from the
command position. It results in pulse differences between these
two positions at any moment. The differences are shown in error
counter. Motor driver uses the error counter as a basic control
index. The large the error counter value is, the faster the motor
speed command will be set. If the error counter is zero, it means
that zero motor speed command will be set.
At following four situations, the ERC signal will be outputted auto-
matically from motion controller to motor driver in order to clear
error counter at the same time.
1. Home return is complete
2. The end-limit switch is touched
3. An alarm signal is active
4. An emergency stop command is issued
4.3.6 Servo ON/OFF switch
The servo on/off switch is a general digital output signal on motion
controller. We define it as SVON pin on the connector. It can be
used for switching motor driver’s controlling state. Once it is turned
on, the motor will be held because the control loop of driver is
active. Be careful that when the axis is vertically installed and the
servo signal is turned off, the axis will be in uncontrolled state. It
could fall on the ground. Some situations like servo alarm and
emergency signal ON will result in the same trouble.