Varian 948, Operation And Service Manual

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Models 947, 948 and 960 Leak Detectors Operations and Service Manual
2-6
2.3 Electronic Considerations for the
Optional Rear Panel Interface
This section includes information necessary to interface the 947/948/960 with a PLC or a
host computer using either serial or parallel communications through the optional rear
panel interface via J120 Discrete I/O, J121 BCD Outputs and J123 Host Serial Port.
2.3.1 Discrete I/O J120 Inputs
The discrete I/O is used to control operations via a PLC. Table 2-2 provides the input
connections.
Table 2-2 J120 Input Connections
Pin on
J120
Input Name Momentary or Level
Description
1 Ground return for J120 only
2 Reject Output Active High Leak rate signal is higher than reject
set point.
3 Stop 200 msec high pulse Unit goes to vent mode.
4 Start 200 msec high pulse Goes to fine test via rough gross modes.
6 Parallel Enable Active High Enables rear panel PLC Interface.
7 Zero 200 msec high pulse Begins Auto Zero routine.
9 Auto Cal 200 msec high pulse Begins Auto Calibrate.
10 Decrement 200 msec high pulse Decrements the exponent when in manual
ranging.
11 Increment 200 msec high pulse Increments the exponent when in manual
ranging.
12 Auto Range Active High Automatically changes the exponent to
keep the reading in range.
14 Hold Places the system in Hold mode.
15 Filament Fault Active High Active when selected ion source
filament is non-functional.
16 Not Ready Active High Not ready to run – possible fault.
18 CAL OK Active High Active when last CALIBRATE successful.
19 Zeroing Active High Active when Auto Zeroing.
21 Calibrating Active High Active when Auto Cal.