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
In case of malfunction the LCD displays the measured concentration, an error code and a key symbol
. On the PCB this
condition is indicated by the yellow „ERR“ LED. The meaning of each error code is included in the attachment "Table of error
codes"
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 and an inscription
starts flashing on the LCD display. 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.
