XDI
(
win
)
–15/30J
(
win
)
TOXIC/OXYGEN – TRANSMITTER
(PCB 337)
www.gds–technologies.co.uk
Technical Sheet ref C1882B
Electrochemical cells
Setting up a pre calibrated Transmitter
(Cell replacement)
New sensors are supplied ready to connect to the system with all jumpers
inserted. This procedure shows how to recalibrate as part of a routine
maintenance or cell replacement.
1. If bench testing the PCB see section B3
2. Using a digital mV meter measure across test pins TP2/3 and
adjust Zero pot RV2 until LED D9 goes green for 4mA (zero) = 4mV
(sensor bridge zero) see B9
3. Apply a known test gas to the sensor (e.g. 100ppm CO) for 1
minute at a flow rate of 1 litre to give a 13mA = 11mV across test
pins TP2/3, adjust gain pot RV4 for correct mV reading.
Power supply
15 to 30Vdc 24v nominal
Outputs
3 wire 4~20mA Direct (WPY)
4 wire CANbus (Addressable) 4~20mA (Y)
Relays
Low alarm
SPCO
(when fitted)
High alarm
SPCO
0.5A @ 30Vdc
Fault alarm
SPCO
Inhibit option during servicing
Logging
Intervals – variable time
Roll over/stop
Storage – 2,880 readings
Requires
USB A to USB micro B cable
PC or laptop (dedicated)
GDS Terminal (download from GDS website)
Setting up a new transmitter utilising
GDS Terminal
1. Insert jumpers J10 and J9 position SO for 4-20mA source
output.
2. Connect sensor to J14 terminal W-white Y-yellow P-pink.
3. For bench setup only – connect 24V + and 0V to J2, connect
jumper to J1 (4~20mA output test load) remove after set up.
4. Rotate Gain pot fully anti-clockwise (minimum span.)
5. When in clean air the sensor bridge is zeroed by adjusting
zero pot until LED D9 is Green.
6. Connect PC to sensor via GDS terminal using USB-A to USB
Micro-B cable at 4800 baud connected to J11. The terminal
output screen shows continuous data output/ commands and
allows input from the PC keyboard.
7. Select COM Port – Note each new sensor connected to
requires a new COM Port to be connected to.
8. Press ‘Space Bar’ loads sensor information. Ensure jumper J17
is fitted before programming. Press (C) to enter Calibration
Mode, and Press ($) to initialize the sensor.
To update firmware contact GDS.
Press W to set 4-20mA parameters, use (L) and (H) to adjust
4mA, Press ‘Space’ to set, use (L) and (H) to adjust the 20mA,
press ‘Space’ to set.
9. Then press (Z) on the PC to zero the reading.
10. Apply a known test gas to the sensor (e.g. 100ppm CO) for
1 minute at a flow rate of 1 litre to give (e.g 12mV = 12mA)
across test pins TP2/3, adjust gain pot for correct mV reading.
11. When using a PC press (S) to enter span mode and using (H)
or (L) adjust the reading. Note – This adjusts the mA reading on
TP2/3 when adjusted.
12. Press (space) to exit span and then (X) to exit the calibration
mode.
13. Connect the sensor to a Combi alarm panel and ensure that it
reports in correctly.
Note: Fit the end of line (EOL) link J3 if the
sensor is to be installed at the end of the sensor cable.
14. If the sensor is fitted with a display – adjust the contrast using
‘VR1’ pot.
15. Remove J1 test link for normal operation, (this does not need to
be removed when used as an Addressable sensor)
16. Ensure J17 address link is removed (this is only used when
changing address from the alarm panel).
17. On completion and when used as an addressable sensor,
future calibrations may be carried out at the Combi alarm
panel.
NOTE:
Oxygen cells only use the P+ and Y terminals J14.
To adjust for the ‘Zero’ it is normal practice to disconnect the green
connector on J14 and adjust the Zero pot until LED D9 is green and
4mA across TP2/TP3. When the cell is reconnected in air at 20.9%Vol
oxygen the span can be adjusted for 17.4mA reading across the same
test pins using the gain pot.
If an LCD option is fitted then calibration and other settings using
magnets instead of a PC can be achieved. See over.
See Reverse for Full list of GDS Terminal Commands
A
C
B
Tox
u/ma
Can Sensor
PCB 337
J12
J4
RELAYS
DISPLAY
SENSOR
CELL
J17
D3
D2
GAIN
J5
J14
J13
J15
+
-
RV2
J7
JTAG
VR1
S
J19
J18
J2
0
ZERO
GAIN
CONTRAST
ZERO
RV4
D9
TEST
J3
EOL
TP1
(W)
(P)
(Y)
ov
TP2
J1
TP10
J16
O2
O2
INV
D5
D10
PROG
ADD
4-20
J11
J10 J9
U14
TP3
4-20mA Pins (mV)
(Steps 2/3)
J9 + J10
(select sink/source)
GDS Terminal
Connection
(Micro USB B)
Gas Status LED
(Step 2)
Gain Pot 20mA
(Step 3)
Zero Pot
(Step 2) (4mA)
Insert jumper J16
when using Oxygen Cells
Fig. 1
