User guide

Command Inputs CME 2 User Guide
72 Copley Controls
Offset
To remove the effects of voltage offsets between the controller and the amplifier in open
loop systems, CME 2 provides an Offset parameter and a Measure function. The Measure
function takes 10 readings of the analog input voltage over a period of approximately 200
ms, averages the readings, and then displays the results. The Offset parameter allows the
user to enter a corrective offset to be applied to the input voltage.
The offset can also set up the amplifier for bi-directional operation from a uni-polar input
voltage. An example of this would be a 0 to +10 Vdc velocity command that had to control
1000 rpm CCW to 1000 rpm CW. Scale would be set to 2000 rpm for a +10 Vdc input and
Offset set to -5V. After this, a 0 Vdc input command would be interpreted as -5 Vdc, which
would produce 1000 rpm CCW rotation. A +10 Vdc command would be interpreted as +5
Vdc and produce 1000 rpm CW rotation.
Monitoring the Analog Command Voltage
The analog input voltage can be monitored in the Control Panel and in the Scope Tool.
The voltage displayed in both cases is after both offset and deadband have been applied.
Analog Command in Position Mode
The Analog Position command operates as a relative motion command. When the
amplifier is enabled the voltage on the analog input is read. Then any change in the
command voltage will move the axis a relative distance, equal to the change in voltage,
from its position when enabled.
To use the analog position command as an absolute position command, the amplifier
should be homed every time it is enabled. The Homing sequence may be initiated by
CAN, ASCII serial, or CVM Indexer program commands.