Kurt J. Lesker 979 Series, Operation And Maintenance Manual

Page: 31 / 54

Series 979 ATV Transducer 31
Pressure Reading – PR1, PR2, PR3
The pressure reading command returns the measured pressure from either
the MicroPirani (PR1), the Hot Cathode (PR2), or a combination of both (PR3).
For pressures above 3x10
-3
Torr, the PR3 reading is the same as PR1. For
pressures below 1x10
-4
Torr, the PR3 reading is the same as PR2.
Query: @001PR1?;FF
Query Response: @001ACK1.23E-2;FF
Set Point Commands
The 979 has three independent set point relays for control. The relay set point
is based on the pressure reported by the
PR3 command (see the Pressure
Reading – PR1, PR2, PR3 command on the previous page).
Set Point Value – SP1, SP2, SP3
The set point value command returns or sets the set point value. The set
point value is the pressure either below or above which the set point relay will
be energized (i.e., N.O. and C contacts will be closed). The direction of the set
point (ABOVE or BELOW) is configured using the
Set Point Direction – SD1,
SD2, SD3 command (next page). The set point must be enabled for the set
point command to function (see the Enable Set Point – EN1, EN2, EN3
command).
Values: Two- or three-digit scientific notation
(default: 1.00E0 Torr)
Query: @001SP1?;FF
Query Response: @001ACK1.00E-2;FF
Command: @001SP1!1.00E-3;FF
Command Response: @001ACK1.00E-3;FF
Hysteresis Value – SH1, SH2, SH3
The hysteresis value command returns or sets the pressure value at which
the set point relay will be de-energized (i.e., N.C. and C contacts will be
closed). The hysteresis value should always be higher than the set point
value. If the hysteresis and set point are the same value, or nearly the same
value, the relay may chatter when the system pressure is near the set point.
Values: Two- or three-digit scientific notation
(default: 1.00E0 Torr)
Query: @001SH1?;FF
Query Response: @001ACK1.10E-2;FF
Command: @001SH1!1.10E-3;FF
Command Response: @001ACK1.10E-3;FF