Danfoss GDA Installation Manual page 4

Gas Detection Controller: Fieldbus wiring - max 96 sensors in total i.e. up to 96 GDU (Basic, Premium and/or Heavy Duty)
Controller
unit
Controller
unit
7
Check of loop completion. Example: 5 x Basic in return loop
Controller Unit
0 V DC
24 V DC
BUS_B
BUS_A
0 V DC
24 V DC

Check of loop resistance: See section: Controller unit multiple GDU commissioning 2. NOTE: Remember to disconnect the wire from the board during measuring.

Check of power polarity: See section: Controller unit multiple GDU commissioning 3.

Check of BUS polarity: See section: Controller unit multiple GDU commissioning 3.
Individual Addresses for the GDU's are given at commisioning, see Controller Unit multiple GDU's commisioning, according to a predetermined "BUS address plan"
8
© Danfoss | DCS (MWA) | 2018.04
Wire length max. 900 meter (2953 ft) per segment.
More segments with additional expansion modules max. 7200 meter (23622 ft).
Additional power limitations must be calculated.
R
R
= Terminating resistor 560 Ohm
= GDU (Basic, Premium and/or Heavy Duty)
R
4

3

2
1
GDU Addr. 01
Ohm

GDU Addr. 05 GDU Addr. 04
560 R
4
3
2
1
V
+
(DC)
+
 
4
3
2
1
GDU Addr. 02 GDU Addr. 03
R
RIGHT
R
WRONG
Danfoss
148H123_03-2018
4
3
2
1
V
(DC)
U = 16 V DC
min
4
3
2
1
DKRCI.PI.S00.F2.02 | 520H12487 | 4