Models 947, 948 and 960 Leak Detectors Operations and Service Manual
2-10
2.4.2 Setup
Parameters relating to the operation and performance of the 947/948/960 Platform are
stored in EPROM. These parameters can be viewed and changed via the service pendant or
rear serial ports.
A standard host computer with an RS-232 port, or PLC is used for connection to and control
of the rear panel serial port (J123). Only the pre-programmed Varian Vacuum Technologies
setup/service pendant is used for connection to and control of the service RS-232 port. The
keypad inputs and instructions (Section A, “Service Pendant Keypad Functions” on
page A-1) are used to determine certain internal operating parameters.
Some parameters are set when the system is assembled and tested. Other parameters are
changed when a gauge is changed or when the ion source or preamplifier is changed. Some
parameters are changed automatically during power up, or when functions such as the
Auto Cal, or Auto Zero run.
2.4.3 Discrete I/O
J120 and J121 connectors contain the discrete I/O lines. This section provides the
information necessary to be able to use discrete I/Os.
The following items relate to the circuits shown in Figure 2-5:
❑
The discrete I/O lines are optically isolated and grouped by connector.
❑
J120 contains status and control inputs and outputs.
❑
J121 contains the BCD and analog voltage leak rate outputs.
❑
The power and return connections to J120 are isolated from J121 and from the
equipment and system grounds.
❑
The power and return connections for the BCD outputs in J121 are also isolated from
J120 and the equipment and system grounds.
Figure 2-5
Discrete Inputs/Outputs Isolated
Summary of Contents for 948
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