Commissioning the System
109 of 132
Publication S177E V2.0 Issue 12/04
The status screen will show 'Waiting for Loopbacks 1', and be followed by 'Finding FCU A’, ‘Finding
FCU B’, ‘Waiting for Loopbacks 2’, ‘Loopbacks Off A’, ‘Loopbacks Off B’ and finally ‘Loopback On’.
Now press '1' to select the master station commands, followed by '4' to select the diagnostic screen.
This is illustrated in section 8.7.4. If all is well on the loop it should show that the reason for the last
loop configuration is ‘Reset Command’ and that there is a loopback at the last field unit.
As the master station progresses through the configuration of the loop it moves through a number of
steps:
1.
It waits for all field units to revert to loopback on. - Waiting for Loopbacks 1
2.
It locates each field unit connected to port A - Finding FCU A
3.
It locates each field unit connected to port B - Finding FCU B
4.
It then waits again for all field units to revert to loopback on - Waiting for Loopbacks 2
5.
It removes loopbacks from field units on A as far as the last one on the loop, which it
leaves in loopback - Loopbacks Off A
6.
It removes loopbacks from field units on B as far as the last one on the loop, which it
leaves in loopback - Loopbacks Off B
7.
It reports the loop status - Loopback On or Off
The master station should have established communication with the furthest field unit. Return to the
Master Station Status page (section 8.5), press 2 to select Field Units, and select the address for the
powered on field unit by using the 'Up' or 'Down' arrow key. The FCU status screen (as illustrated in
section 8.9.1) will show if communication is established.
Now switch on the next nearest field unit, change the display to show its status using the ‘Up’ or
‘Down’ arrow key and check that communication is established with it and the last field unit. There is
no need to reset the loop as this unit has been introduced between the master station and the field
unit in loopback and communication with it should be quickly established. If there is a fault on the loop
wiring this will prevent the master from communicating to this field unit.
Successively progress backwards round the loop powering 'on' each field unit and establishing
communications. Faults should be corrected as you go. Switch the display between the field unit being
checked and the Master Station Status screen to make sure that communications are satisfactory. If
the master station fails to locate a field unit, or goes into the reconfiguration process use the
diagnostic screens to establish why. Finally you will end up with all the field units in communication
with Port A.
Next connect the Port B wires and disconnect the Port A wires, reset the loop and check that there is
only one loopback at the field unit nearest Port A.
Finally re-connect the Port A wires, reset the loop and check that there are no loopbacks anywhere,
and that all the field units are in communication with the master station. Verify that status changes in
the field are reported to the appropriate field unit screen, and that commands can be issued to every
field unit.
