HELIX GRANVILLE-PHILLIPS Convectron ATM, Instruction Manual

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Chapter 4
52
Convectron
®
ATM Vacuum Gauge Module Instruction Manual
The plus (+) or minus (–) sign that precedes the pressure value is
meaningful only if the relay will indicate differential pressure.
If the relay is assigned to vacuum chamber pressure, you should not
enter a + or – sign preceding the “A” and “D” pressure values.
• If you enter a + sign, the sign will be disregarded.
• If you enter a – sign, the module will return a RANGE ER response.
If the relay is assigned to differential pressure, enter a + sign or a – sign
preceding the “A” and/or “D” pressure values.
• The + sign will cause the relay to switch states when differential
pressure is positive (when vacuum chamber pressure is greater than
atmospheric pressure).
• The – sign will cause the relay to switch states when differential
pressure is negative (when atmospheric pressure is greater than
vacuum chamber pressure).
The + or – that follows the pressure value is the exponent. For example:
• A pressure value of “2.00E–2” equals 2 x 10 –2 Torr, or 0.020 Torr.
• A pressure value of “2.00E+2” equals 2 x 10 2 Torr, or 200 Torr.
Table 4-10 explains the PC command structure.
Table 4-10 Command structure for relay settings
Address field Command field
Activation pressure
deactivation pressure,
or OFF
Increasing/decreasing
differential pressure
Pressure value
#XX PCX A or D or O + or – sign X.XXE+Y or
X.XXE–Y
“XX” is 2-digit
address • PC1: relay 1
• PC2: relay 2
• PC3: relay 3
• PC4: relay 4 Enter “A” value in one
command and “D” value in
another command or enter
“O” for OFF:
• A: activation pressure
• D: deactivation pressure
• O: relay OFF (disabled) I or – sign if relay is
assigned to differential
pressure
• + for positive differential
pressure
• – for negative differential
pressure
• 2 significant digits
• “E” constant
• Signed exponent
(+ or –)
• 1-digit exponent