SL-24533.book(SL-24533 FC.fm) - Emerson Network Power

Figure 3
Option Location and Mounting Detail
3.2 CANbus Termination
The CANbus in the Npower system is used to communicate system status, history data and commands to various
logic boards in the system. To perform in a reliable manner the CANbus must be properly terminated on each end
of the CANbus with a 120 ohm resistor. This is accomplished by connecting the terminating resistor in the first
and last unit on the CANbus. There are different means to accomplish this depending on which option or logic
board is on the end of the bus. The UPS Control Board is considered to be the first element on the bus and has a
permanent termination resistor installed on it. In a standard system with no options installed the second terminator
is installed via a jumper in the MicroMonitor board. The Remote Status Panel (RAS), Open Comms Discrete
Input (OCDI) and Open Comms Discrete Output (OCDO) options have built in termination resistors that are
enabled with a jumper.
NOTE
On a fully optioned Npower there will more than one CANbus utilized. Refer to
Figure 4 for a diagram of a basic Npower without options.
Figure 4
Diagram of a Basic Npower Without Options
UPSC
MM
PS
TR TR TR
Conn
Figure 1
In Figure 4 the CANbus is terminated on the UPS Control Board that connects to the MicroMonitor (MM) board
and to the Power Supply. The Power Supply provides an electrical connection point for the CANbus in addition
to power for the CANbus. It does not actively connect to it. The final CANbus termination is on the Micro Monitor
board.
8 General information concerning 4 x 7 Option Cards