Operation; Analogue Output Protocol - Simtronics GD1 MK3 Operating Manual

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
Normal gas reading
Early Dirty Optics
Warning
(90% signal
reduction)
Beam block,
Alignment mode or
Service mode
Fault
or
Init mode (booting
up)
No power
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.
GD1
Analogue
1
output 1
3
4 - 20 mA
3 mA
2 mA
1 mA
< 0.5 mA
Analogue
2
output 2
0 – 14 mA
2 - 10 %
0 - 2 %
Err
Err
Page 39 of 76
Comment
4 mA = 0% full scale
20 mA = 100% full scale and
higher
Detector will still output gas
concentration if reading is >
10 % full scale.
Default 60 sec delay before
entering beam block.
No gas detection.
No gas detection.
No gas detection.
850-816926-EN R06