CRESTRON
CNTBLOCK
Network Terminal Block
R E M O T E C O N T R O L S Y S T E M S
2
DOC. 8055A
Specifications subject to change without notice.
INDICATORS:
NOTE
Indicators are provided to denote an error with the net cable supplying network
power to the CNTBLOCK. The LEDs do not signify wiring problems that exist on the
network runs from the CNTBLOCK to other net devices.
There are three LED indicators located on the CNTBLOCK top panel, refer to figure 1. The combination of
two LEDs, NORM ON (Y) and NORM OFF (Z), and their three states of illumination, bright, dim, and off,
indicate whether wiring through the CNTBLOCK is correct. Refer to table 2 for LED illumination
combinations and the associated wiring conditions.
Table 2. Wiring Conditions Per CNTBLOCK LED Illumination
CNTBLOCK LED ILLUMINATION
POSSIBLE WIRING CONDITIONS
NORM ON (Y)
NORM OFF (Z)
Correct
Bright
Dim
Both net wires disconnected
Off
Bright
Data Y net wire correct only
Bright
Bright
Data Z net wire correct only
Off
Dim
Data net wires swapped
Dim
Bright
POWER
The green LED illuminates when 24 volts is supplied to the CNTBLOCK over the network. If the +24V
line is improperly connected, the POWER LED does not illuminate.
NORM ON (Y)
The red LED brightly illuminates in combination with an illuminated POWER LED and a dimly illuminated
NORM OFF (Z) LED during normal operating conditions. Refer to table 2 for other states of illumination.
NORM OFF (Z)
The red LED illuminates dimly in combination with a brightly illuminated POWER and NORM ON (Y) LED
during normal operating conditions. Refer to table 2 for other states of illumination.
INSTALLATION/SETUP:
Power Isolation
If additional power supplies are needed for a CRESNET II system, care must be taken to isolate
them from one another. The CNTBLOCK offers a convenient method for isolating network devices
which should be powered by separate power supplies. Removing the jumper from the circuit
board isolates the 24 V lines from one side of the CNTBLOCK to the other. The jumper is clearly
marked (JUMPER) on the circuit board.
