OJ Electronics GreenZone Module MP-Bus Instruktionen Seite 14

English
Symptom
Display shows "SC"
VAV damper or
heating/cooling valve
inoperative
14
Cause
Poor or no connection in
Modbus cable
Defective OJ GreenZone™
Master
Defective OJ GreenZone™
Module MP-Bus
Sensor short-circuited
No voltage supply to OJ
GreenZone™ Module
MP-Bus
Actuator supply terminals
lack 24V AC:
(+18- 20)
(+21- 23)
(+24- 26)
(+27- 29)
Defective OJ GreenZone™
Module MP-Bus
Fault in the electrical con-
nections
Defective valve or VAV
actuator
© 2017 OJ Electronics A/S
OJ GreenZone™ Module MP-Bus
Action
Check Modbus cable.
Configuration of Modbus cable and connector
is shown in figs 6 and 7.
Repair or replace defective Modbus cable.
Replace OJ GreenZone™ Master.
Replace OJ GreenZone™ Module MP-Bus.
Check the connected PT1000 sensor.
The sensor should be connected to the RJ12
connector marked "L" in fig. 3 – correct
connection is shown in fig. 10.
Check sensor resistance.
The measured resistance should be
approximately 1078 Ω at 20°C.
Check that there is 24V AC on entry terminals
1 and 2 and exit terminals 3 and 4.
If there is no voltage on exit terminals 3 and 4,
the components supplied from these terminals
(3 and 4) have either short-circuited or are
overloaded.
Remove the wires connected to the terminals
and check whether there is voltage across the
terminals.
If, once the load has been removed, voltage
can be measured across the terminals, it is
highly likely that the wires connecting the
actuator are short-circuited. Remove the short
circuit and reconnect the actuator. Check the
voltage again.
Remove the wires connected to the terminals
and check whether there is voltage across the
terminals.
If, once the load has been removed, voltage
cannot be measured across the terminals, it is
highly likely that the OJ GreenZone™ Module
MP-Bus is defective.
Replace OJ GreenZone™ Module MP-Bus.
Check electrical connections.
Replace actuator.