Configuration and Installation Chapter 2SCXI-1120 User Manual 2-6 © National Instruments Corporationacquisition board, those different modules will have jumpers similar to W43 and W42 of theSCXI-1120. Set those jumpers on the different modules using the same method described herefor the SCXI-1120.On Revision A and B SCXI-1120s, jumper W42 is not used. You set jumper W43 as explainedin the cases above, except in the case of a multichassis ribbon cable system. In a multichassisribbon cable system with Revision A and B SCXI-1120s cabled to the data acquisition board,you can access the MISO line in only one chassis. Pick one of the chassis that has theSCXI-1120 cabled to the DAQ board. Set jumper W43 on the SCXI-1120 to position 1. On theSCXI-1120s that are in the other chassis and cabled to the data acquisition board, set jumperW43 to position 3. Notice that you will only be able to access digital information from thechassis that has the SCXI-1120 with jumper W43 set to position 1.On Revision C and later modules, the SERDATOUT line is driven with an open-collector driver(a driver that actively drives low or goes to a high-impedance state, relying on a pullup resistor tomake the signal line go high). When using a single chassis, leave W42 and W43 in position 1,the factory default, on the SCXI-1120 that is connected to the data acquisition board. In thissetting, the module drives MISO to SERDATOUT and connects the necessary pullup resistor tothe SERDATOUT line. When using multiple chassis, leave jumper W43 in position 1 on all ofthe SCXI-1120s that are cabled to the data acquisition board. Only one of the SCXI-1120s thatare cabled to the data acquisition board should have jumper W42 in position 1. It does not matterwhich of the SCXI-1120s that are cabled to the data acquisition board has the pullup connected.All of the other SCXI-1120 modules that are cabled to the data acquisition board should havejumper W42 in position 3. The reason for this is that if too many pullup resistors are attached tothe SERDATOUT line, the drivers cannot drive the line low. See Table 2-1 for the descriptionand configuration of the jumper settings.Table 2-1. Digital Signal Connections, Jumper SettingsJumper Description ConfigurationW42W42W43W43Connects pullup to SERDATOUT(Revision C and later) factory-default setting.Parking position (not connected onRevision A and B)Connects MISO to SERDATOUTFactory-default setting.Parking position•••321•••321•••321•••321(continues)
