52
MANUAL P/N 316005 REV: B
Figure 5-1 Pin Assignments/Connector
5.3 Process Control Operation
At all times the status of the 6 relays are displayed in the relay status LEDs on the 316 front panel. The LEDs
do not indicate whether the gauge pressure is above or below the programmed setpoint, since setpoint
polarity and manual override status can result in activation above or below the setpoint.
Figure 5-2 Process Control Relay Status Lights
5.3.1 Setpoint Display and Adjustment
Setpoints are stored in non-volatile memory, and are specified by a 1-digit mantissa and 1-digit exponent.
They can be set anywhere in the range 1 x 10
-5
to 9 x 10
+5
. This allows for the entire pressure range of all
supported transducer types and systems of units. The setpoint is displayed in scientific notation.
The setpoint is compared directly to the display data, so units of measure are implicit. Changing the units
switch on the gauge control modules will not change the stored setpoints. They must be re-programmed in
the new system of units.
If a setpoint is set to "above atmosphere", the relay will always be activated (unless its polarity is reversed,
see "Relay Polarity Setting" in this section), except during overflow conditions that occur, e.g. when a
Convectron gauge is disconnected. If it is desired that a process control be held in one state, the manual
override switch should be used. If the setpoint is adjusted below 1 x 10
-5
to 0, it will always be deactivated
(unless polarity is reversed).
