12
ENG
+0300046IE - rel. 1.2 - 14.01.2021
3. OPERATION
3.1 Start-up cycle
When power is connected, the device begins the start-up cycle, divided
into two phases:
•
start-up
•
warm-up
The start-up sequence lasts around 7 seconds, during which the main
functions of the gas detector are initialised and verified. In particular, the
following are activated:
•
LED
•
buzzer (if not previously disabled via app)
•
the 3 relays
•
the analogue output
•
the Modbus output
•
the sensor connection
At the end of the start-up sequence, the warm-up phase commences,
during which the sensor output signal is adjusted and stabilised.
In the warm-up phase, the green LED flashes at a frequency of 0.5 Hz and
the analogue output sends the signal for the warm-up phase, as shown
in the table under “Analogue signals”.
The duration of the warm-up phase depends on the sensor technology
used.
Semiconductor = 5 min
Electrochemical = 5 min
Infrared = 2 min
The duration of the warm-up phase may also vary according to
environmental conditions. In this phase it is important not to cause
sudden changes in gas concentration, so as to avoid compromising
correct measurement by the sensor.
IMPORTANT
: the sensors may take longer to warm up than
specified; in these cases, do not take any action, wait for the device to
stabilise. The time needed for complete stabilisation of the device may
vary from 2 hours (minimum time) to 24 hours (recommended time).
3.2 Analogue signals
The Carel GLD gas detector features a single configurable analogue
output. During normal operation, the device’s analogue output signal is
proportional to the gas concentration measured, and can be selected
from the following options.
•
1 to 5 V
•
0 to 5 V
•
2 to 10 V
•
0 to 10 V
•
4 to 20 mA (default)
The Carel GLD series gas detectors uses different voltage/current
values to indicate different operating modes. In normal operation, the
gas concentration is indicated by the analogue output signal level. The
relationship between output signal level and gas concentration is shown
below:
Gas concentration
1-5 V
0-5 V
2-10 V
0-10 V
4-20 mA
0%
1 V
0 V
2 V
0 V
4 mA
50%
3 V
2.5 V
6 V
5 V
12 mA
100%
5 V
5 V
10 V
10 V
20 mA
Tab. 3.a
The device can also have several special states, indicated by specific
analogue output levels as shown below:
Operating mode
1-5 V
0-5 V
2-10 V
0-10 V
4-20 mA
Device fault
≤ 0.3 V
N/A
≤ 0.6 V
N/A
≤ 1.2 mA
Offline / maintenance
/ warm-up mode
0.75 V
N/A
1.5 V
N/A
3 mA
Drift below zero
0.95 V
N/A
1.9 V
N/A
3.8 mA
Measurement range
exceeded
5.12V
5.12V
10.25 V
10.25 V
20.5 mA
Analogue interface fault
> 5.25 V > 5.25 V > 10.5 V > 10.5 V > 21 mA
Tab. 3.b
3.3 Modbus signal
The Carel GLD series gas detectors feature a Modbus RTU digital interface.
All of the status messages and most of the parameters accessible and/
or configurable via the Bluetooth® interface are also accessible and/or
configurable via a Carel Modbus controller. For details on the Modbus
registers, see 5.4 “Modbus registers”.
3.4 Device operating states
The Carel GLD series gas detectors provide audible and visual indications
of their current operating status, in addition to the relay outputs. Visual
indication of device operating status is provided by a three-colour LED
(green/red/orange).
Device status and the corresponding outputs are shown in the following
table:
Status
LED
LED freq.
Buzzer
Buzzer.
freq.
Relay 1
(LOW)
Relay 2
(HIGH)
Relay 3
(fault)
Warm-up
1 Hz
OFF
OFF
OFF
OFF
Normal
Cont.
OFF
OFF
OFF
OFF
Low alarm
1 Hz
1 Hz
ON
OFF
OFF
High alarm
2 Hz
2 Hz
ON
ON
OFF
Offline
1 Hz, seq.
OFF
OFF
OFF
OFF
Fault
Cont.
Cont.
OFF
OFF
ON
Negative gas
fault
2 Hz
Cont.
OFF
OFF
ON
Zero calibra-
tion
fault
2 Hz
OFF
OFF
OFF
OFF
Full-scale cali-
bration fault
2 Hz
OFF
OFF
OFF
OFF
Tab. 3.c
3.5 Functions of the switches
Users can interact with the gas detector via the switches. The GLD series
gas detectors feature two pairs of switches: two physical switches (push-
buttons) and two magnetic switches. In this manual, the physical buttons
are denoted as TACT#1 and TACT#2, and the magnetic switches as MAG#1
and MAG#2.
The functions of the two pairs of switches are the same, except for the
factory settings reset function, which can only be activated via physical
buttons or via the app. To reset the device to the factory settings, press
and hold TACT#1 and TACT#2 buttons together for 30 seconds, the device
will then be reset to the factory settings.
The device recognises two input levels, based on the duration: “TOUCH”
and “HOLD”.
To activate a “TOUCH” function, press or magnetically activate the chosen
switch for 1 second, until a single beep is emitted. Then release the switch.
To activate a “HOLD” function, press or activate the chosen switch using a
magnetic stylus for > 5 seconds, ignoring the single beep for the “TOUCH”
function. Continue holding/enabling the switch until a double beep is
emitted. Then release the switch.
If the switch is pressed for > 30 seconds, the “Switch blocked” fault will be
activated (code 0x00008000).
The function of each switch depends on current device status. See the
table below for the functions of the switches in each device status.
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