8
9.
Communication protocol switch DEGA/MODBUS
Plugging a jumper in the JP1 connector will swtich from the DEGA communication protocol to the
MODBUS communication protocol.
Transmitter functions
The detector's motherboard is equipped by status LEDs, which help in detecting problems during the installation.
LED „POW“ shines at correct power
LED „TxD“ flashes when transmitting a packet via RS485
LED „RxD“ flashes when a packet is correctly recieved via RS485
LED „ERR“ shines/flashes in case of malfunction or substandart situations
1.
Turning on the transmitter
After turning on the power the LED "POW" starts shining and the LED "ERR" starts flashing, indicating a forming
sequence of the sensor and automatic testing procedures, which can take up to 180s depending on the sensor used.
The output of the current loop is 1mA. During this sequence, testing of internal electronics and stabilization of the
sensor in order to eliminate false alarms after turning on, is taking place. At this time, the display only shows the
time to the beginning of the measurement loop.
After completion of the formation, a 4mA current begins to flow on the output of the current loop and the
transmitter starts working according to it's settings.
2.
Gas detection
The transmitter continuously measures the detected gas concentration in the atmoshpere and converts it's current
value into a 4-20 mA signal or transmits it's value to the evaluation unit via DEGA/MOBUS protocol.
3.
Malfunction
If a malfunction of electronics or the sensor is detected during operation, the transmitters starts transmitting via a
0,5mA current loop. On the PCB this state is indicated by the yellow LED "ERR"
4.
Monitoring the calibration periods
The transmitter continuously checks the calibration validity of the connected sensor.
After 12 months since the last calibration (Max. calibration interval) the LED "ERR" starts flashing. The connected
sensor must be calibrated immediately. The transmitter will transmit the information about the ending calibration
via current loop. The transmission will be the following: 10s transmitting a 4-20mA signal informing about the actual
gas concentration following a 1 second interval of 2mA current.
5.
Reading the record of measured concentrations and alarms
The transmitter periodically after 60s stores the current detected concentration into it's internal memory. The
internal memory retains data from the last 64260 measurements (cca 44 days). In order to read this information,
the program DegaConfig is required. Refer to the DegaConfig program instruction.
Operation, maintenance, inspection and service of the transmitter
1.
Usage limits
To maintain proper operation of the transmitter it is neccesery to respect the fact, that step changes of humidity,
condensation or rapid changes of pressure can cause incorrect indication of the measured value. Each sensing technology is
suited for different methods of application, which is described below. All sensors are characterized by a smaller or larger cross-