6 Operations and Functions
6-3. External output operation
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SD-1DGH
CAUTION
•
The 4 - 20 mA output is already adjusted. In case of over scale, an output will not exceed 22 mA.
•
Output during INHIBIT or initial clear is based on 4 - 20 mA output setting in the maintenance
mode.
In particular, when the detector is started or the specification is changed, be careful about 4-20
mA output setting. Understand how the detector functions, and take actions, if necessary, so that
the signal receiver side can prepare to avoid false alarms.
6-3. External output operation
Signal Transmission System
Electric current transmission (non-isolated) 4 – 20 mA
Transmission Path
CVVS
Transmission Distance
CVVS 1.25 sq: Maximum 1 km
Connection Load Resistance
Below 300
Ω
1
Detection Mode (No Alarm)
4 - 20 mA (concentration output)
2
Detection Mode (Gas Alarm)
4 - 20 mA (concentration output)
3
Initial Clear
Depending on the setting of section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: 4 mA
4
Maintenance Mode
2.5 mA setting: 2.5 mA
4 mA setting: 4 mA
HOLD setting: The previous value retained
4 - 20 mA setting: 4 - 20 mA (concentration output)
5 Alarm
Test
Output
ON
setting: 4 - 20 mA (concentration output)
Output OFF setting: 4 mA
6
Fault Alarm
0.5 mA (Fixed)
7
INHIBIT
Depending on the setting of section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: 4 mA
8
Power Off
0 mA
Example of Gas Concentration and External Output
4 - 20 mA specification
(Maintenance output: 2.5 mA setting)
2.5 mA
4 mA
20 mA
22 mA
Full scale
Gas concentration
External output
0
Zero
suppression
Detection Mode
Maintenance Mode
