MKS UniMag 971, Operation And Installation Manual, Page: 16 / 44

971 UniMag ™ Operation manual 13
Enter pressure
+5.00E-6 Torr
Enter pressure
+6.00E-6 Torr
Direction 1
BELOW
Enable 1
ON
When using the setpoint relay to control process equipment, always take
appropriate precautions to prevent system damage in case of transducer power
failure. The NC contact will be closed in case of transducer power failure.
 If the transducer is supplied as a special version (P/N: 971-xxxxx-xxxx) with pre-configured
parameters such as setpoint settings, the setup is per default locked. The transducer will reply with
error code “NAK180” if the user tries to change parameters. To change pre-configured parameters
refer to unlock procedure page 19.
Setpoint setup by Serial interface
The correct procedure for setting up set point parameters are:
1. Enter set point value 5.00E-6 Torr
Command: @253SP1!5.00E-6;FF Reply: @253ACK5.00E-6;FF
2. Select setpoint direction (ABOVE/BELOW)
Command: @253SD1!BELOW;FF Reply: @253ACKBELOW;FF
3. Enter setpoint hysteresis value, if other than d/- 10% of set point value is required.
Command: @253SH1!6.00E-6;FF Reply: @253ACK6.00E-6;FF
4. Enable setpoint (OFF, ON)
Command: @253EN1!ON;FF Reply: @253ACKON;FF
Setpoint setup by PDR900 Controller
1. Edit > Setpoint > Setpoint 1> Setpoint Value 1
Enter set point value 5.00E-6 Torr
2. Edit > Setpoint > Setpoint 1> Direction 1
Select set point direction
3. Edit > Setpoint > Setpoint 1> Hysteresis 1
Enter set point hysteresis value
Only if other than d/- 10% of set point value is required.
4. Edit > Setpoint > Setpoint 1> Enable 1
Enable set point
Setpoint value
The setpoint value is the pressure either below or above which the setpoint relay will be energized.
Setpoint hysteresis value
The hysteresis value is the pressure value at which the setpoint relay will be de-energized.
Setpoint direction
The setpoint direction determines whether the relay is energized above or below the set point value.
Enable setpoint
The enable setpoint command enables, disables or enable the setpoint relay.

The 971 transducer has an auto hysteresis setting of 10% of the set point value that
overwrites the current hysteresis value whenever the set point value or set point
direction is changed. If other hysteresis value than 10% is required, first set the set
point value and set point direction before setting hysteresis value.