Convectron Gauge Test; Testing Convectron Gauge - HELIX GRANVILLE-PHILLIPS Convectron ATM Instruction Manual

Chapter 5
Table 5-3 Troubleshooting RS–485 responses related to data entry or inability to process a command
Message from
module Possible causes
COMM ER Parity error in command from host.
NVRAM ER Module cannot write data to non-volatile memory
(NOVRAM).
RANGE ER Pressure value in TS or TZ calibration command is
outside allowable limits.
SYNTX ER • Command was improperly entered.
• Module does not recognize command syntax.
5.3

Convectron gauge test

66
Performing a Convectron gauge test with instruments
that apply more than 0.1 V with the gauge at vacuum
chamber pressure can result in property damage.
Do not perform a Convectron gauge test with an instrument that
applies more than 0.1 V of electromotive force.
Even a small amount of voltage can damage the small diameter sensing wire
inside the Convectron gauge.
To determine if the Convectron gauge sensing wire has been damaged,
follow these instructions:
1. Remove the Convectron gauge as instructed on pages 68–68.
2. Use a low-voltage (maximum 0.1 V) ohmmeter to check resistance
values across the pins on the base of the gauge. Pin numbers are
embossed on the base. Figure 5-1 illustrates the base of the gauge.
The resistance across the pins should be within the ranges listed in
Table 5-4. If resistance across pins 1 and 2 is not approximately 20 to 30 Ω
or if other listed resistance values are greater than the listed values, the
gauge is defective. Install a replacement Convectron gauge as instructed on
page 69.
Convectron
Solution
Verify that parity from host matches parity
configuration for module.
1. Send FAC command to reset module to factory
defaults.
2. Re-send process control, set, or calibrate
command.
3. Return module to factory (see page 70).
• If TS value is too high, enter an atmospheric
pressure value < 399 Torr (see page 56).
• IF TZ value is too low, enter a vacuum chamber
pressure value > 1 x 10
Re-enter command using proper character string
(see pages 59–60).
CAUTION
®
ATM Vacuum Gauge Module Instruction Manual
–1
Torr (see page 56).