INFICON T-Guard Leak Detection Sensor - Manual (Page 53)

Operation
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Notice When using the continuous measurement mode, a trigger level cannot be
set. That is why you have to stop the measurement yourself as soon as you
see that the sensor current gets too high. In Continuous mode, the T-
Guard™ Leak Detection Sensor switches over to the reference line when
the sensor flow is greater than 1x10
-8
A.
5.4 Controlling via PLC
Basic functions and values of T-Guard™ Leak Detection Sensor can be controlled
and read by a PLC. Refer to chapter 4.6 for a detailed listing of all PLC commands
and signals.
Select PLC inputs in:
Main Menu
→
Settings
→
Interfaces
→
Select PLC Inputs.
Select PLC outputs in:
Main Menu
→
Settings
→
Interfaces
→
Define PLC-outputs
PLC outputs 1 - 4 are connected to the LEDs 1 - 4.
The measured leak rate is available at the RECORDER output.
5.4.1 How to execute an accumulation measurement
You can start the measurement when READY is low-resistive.
During the measurement, the MEASURE output is low-resistive.
After the measurement, the MEASURE output is high-resistive. When the REC.
STROBE output will be high-resistive again, you can read the analog outputs. This
will happen after about 300 ms.
If the AUTOMATIC PURGING is enabled. READY will be low-resistive after purging.
Only then, the next measurements can be started.
5.4.2 How to execute a carrier gas measurement
You can start the measurement when READY is low-resistive.
During the measurement, the MEASURE output is low-resistive.
After the measurement, the MEASURE output is high-resistive. When the REC.
STROBE output will be high-resistive again, you can read the analog outputs. This
will happen after about 300 ms.
After the reference measurement, the READY output will be low-resistive again. This
takes as long as the FINE-measurement time. Only after the cycle has been finished,
the next measurement can be started.
5.5 Controlling via RS-232
Nearly everything that can be done with the control unit can also be done via the
RS232 connection to a PC.
The Interface Description document explains how to do this (iins85e1-a).