Simtronics GD1 MK3 - GD1 Operation Modes; Analogue Output Protocol Details

GD1 Page 39 of 76 850-816926-EN R06
4. OPERATION
The GD1 has no user adjustable parts inside. Do not open the GD1 housing, as
this will change the internal atmosphere, and the initial calibration could be
affected. Opening the GD1 also voids all warranty offered at the time of sale
The GD1 has no user controls or adjustments (except for the specified HART® settings). Gas
reading and fault signaling is given through the 4-20 mA current loop interface.
4.1. Analogue Output Protocol
Condition
Analogue
output 1
1
Analogue
output 2
2
Comment
Normal gas reading
3
4 - 20 mA
0 – 14 mA
4 mA = 0% full scale
20 mA = 100% full scale and
higher
Early Dirty Optics
Warning
(90% signal
reduction)
3 mA
2 - 10 %
Detector will still output gas
concentration if reading is >
10 % full scale.
Beam block,
Alignment mode or
Service mode
2 mA
0 - 2 %
Default 60 sec delay before
entering beam block.
No gas detection.
Fault
or
Init mode (booting
up)
1 mA
Err
No gas detection.
No power
< 0.5 mA
Err
No gas detection.
1. The gas reading is clipped at 3.75 mA and 20 mA and will not go outside this range as
long as the GD1 is in Measurement mode.
2. Relative transmission.
3. As a default the zero filter is activated. The zero filter removes any fluctuations below
10 %FS. So the analogue output will show 4 mA as long as the measurement is below
10 %FS.