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Instruction Manual
NOTES:
1. All Responses are 13 characters long.
2. xx is the address of the device. (00 thru FF)
3. <CR> is a carriage return.
4. _ is a space.
5. The 'z' in the set or read trip point commands is a + or -. The plus is the 'turns on below' point and the
minus is the 'turns off above' point.
6. All commands sent to the module start with a '#' character, and all responses from the module start with
.
a '*' character
7. This protocol was designed to be 100% compatible with the Helix Mini-Convectron
8. A valid address must be used even in RS232 commands. Factory default is 1.
Service
Maintenance
Under normal circumstances, there is no routine maintenance required for your VGC-301 Controller. Good
manufacturing practice suggests that all measuring instruments should be periodically calibrated against known
calibration standards.
Cleaning
The most common cause of all vacuum gauge failures is contamination of the sensor. Refer to the instruction
manual for your gauge for more information. Appendix C also contains a more complete discussion of
contamination and cleaning procedures.
Troubleshooting
Indication
Display is off / blank
Display reads "Sensor Bad"
Readings appear very different
from expected pressure
Readings are noisy or erratic
Gauge cannot be calibrated - zero
and span (vacuum & atm)
Setpoint does not actuate
InstruTech, Inc
InstruTech VGC-301 Convection Vacuum Gauge Controller
Possible Cause
No power
The gauge tube or gauge cable is
disconnected.
The gauge tube is bad.
The process gas is different from
the gas used to calibrate the
gauge.
The gauge and VGC-301 have not
been calibrated or have been
calibrated incorrectly
Loose cables or connections
Contamination
Contamination.
Sensor failure for other cause.
Incorrect setup
®
.
Possible Solution
Check cable connections and verify
that power is being supplied.
Check gauge cable connections.
Replace gauge tube.
Correct readings for different gas
thermal conductivity.
See Appendix B.
Check that zero and atm are
adjusted correctly.
Check and tighten connections.
Inspect gauge for signs of
contamination such as particles,
deposits, or discoloration on gauge
inlet. Try cleaning if appropriate.
Replace or clean the gauge. See
Appendix C on cleaning.
Replace gauge.
Check setpoint setup
page 12
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