NT8D41AA Serial Data Interface Paddle Board Page 671 of 906Circuit Card Description and Installationa socket in the CPU area of the backplane allows it to work only when thatCPU is active.The SDI paddle board is normally installed into a socket in the network areaof the backplane. This allows it to be accessed by either of the systemprocessors. This is necessary because the active CPU switches automaticallyeach night at midnight, and whenever a fault occurs on the active CPU card.The SDI paddle board can also be installed into a socket in the CPU area ofthe backplane. This is done when performing maintenance or an upgrade onthe system. The SDI paddle board is plugged into the CPU that is not theactive system CPU. One of the serial ports on the SDI paddle board is thenconnected to a maintenance terminal and the CPU board is put intomaintenance mode. Diagnostics can then be run from the maintenanceterminal without having to stop the system. This is also used to perform aparallel reload of the system software without affecting the operation of theswitch.Connector pin assignmentsThe RS-232-C signals for port 1 are brought out on connector J1 and theRS-232-C signals for port 2 are brought out on connector J2. The pinouts ofJ1 and J2 are identical, so Table 211 can be used for both ports.Table 211Connectors J1 and J2 pin assignments (Part 1 of 2)Pin # Signal Purpose in DTE mode Purpose in DCE mode1 CD Carrier detect (Note 1) Carrier detect (Not used)2 RD Transmitted data Received data3 TD Received data Transmitted data4 DTR Data terminal ready Data terminal ready (Note 2)5 GND Ground Ground6 DSR Data set ready (Note 1) Data set ready7 RTS Request to send (Not Used) Request to send (Note 2)
