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MANUAL P/N 316005 REV: B
scrolled through this stored pressure value, the relay will change state unless the manual override switch is in
a manual operation position.
There is a programmed 10% hysteresis on each process control setpoint. For example, with a pressure
setpoint of 6.3 Torr the relay will activate when the display reaches 6.2 Torr (for falling pressure) and will
deactivate when the pressure rises to one significant digit above the setpoint plus 10%, i.e., 6.3 + 0.6 + 0.1 or
7 Torr. For setpoints where the 2nd digit is 0.5 or greater the 10% value is rounded up. For example, if the
setpoint is programmed to 6.6 Torr the relay will activate at 6.5 Torr (on falling pressure) and will deactivate
when the pressure rises to 6.6 + 0.7 + 0.1 or 7.4 Torr.
Since the process control and computer interface modules derive their pressure data directly from the display
bus, they will be unable to update their pressure data while setpoints are being displayed. They will not
mistakenly interpret setpoint data as pressure data, but will simply retain the last displayed pressure data until
the SET key is released.
If the thumbwheel setting is changed while a setpoint is being displayed, this change will not take effect until
the display has been released and the SET key depressed another time.
Relay Polarity Setting
The relays can be set to activate with pressure either above or below the setpoint. A switch is provided for
each channel. For activation below the setpoint, the switch should be in the OFF position. This is the factory
setting.
Refer to the numbers on the printed circuit board, not on the switch body itself, for the channel number.
Figure 5-4 Process Control Module, Top View
(Controller Cover Removed)
