Nevion FR-2RU-10-2 - Manual (Page 9)

FR-2RU-10-2 Rev. N
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In case of power failure, pins 3 and 7 will be physically connected (low impedance),
otherwise the connection between pins 3 and 7 will be high impedance.
4.2 RS-422 connection
At the rear end of the sub-rack is an RS-422 bus. When used in combination with the
GYDA-SC Rack System Controller, up to 8 sub-racks can be controlled. On the rear
end of the sub-rack are DIP-switches where each sub-rack can be assigned its own
address (see figure 3).
The RS-422 interfaces are shown in figure 3.
4.2.1 Pin-out RS-422 (RJ45)
Pin #1
Rx A (+)
Pin #2 Rx B (-)
Pin #3 Tx A (+)
Pin #4 Reserved
Pin #5 Reserved
Pin #6 Tx B (-)
Pin #7 Not Connected
Pin #8 Not Connected
Figure 4: RS-422 pin-out.
4.2.2 Connecting several sub-racks together
Several sub-racks can be connected to each other through the RS-422 ports on the
rear of each sub-rack.
One GYDA-SC controller can control maximum 8 sub-racks.
You start with the sub-rack containing the GYDA-SC Rack System Controller, and use
1 RS-422 port to loop through to the next.
The last sub-rack connected must be terminated with 110

in order to ensure proper
operation. The other port of the rack containing the GYDA-SC controller must be left
open, and cannot be connected to other sub-racks.
Figure 5 shows an example of how to connect 8 sub-racks together as seen from the
rear end. By using the RS-422 interface at the GYDA-SC controller card, we control 8
sub-racks via one RS-422 bus.