Chapter 2 Connecting Signals© National Instruments Corporation 2-11 SCXI-1503 User ManualRear Signal Connector DescriptionsThe rear signal connector on the cabled module is the interface betweenthe DAQ device and all modules in the SCXI chassis. AI 0 is used todifferentially multiplex all 16 channels, the CJ sensor, and analog signalsfrom the modules to the connected DAQ device.The communication signals between the DAQ device and the SCXI systemare listed in Table 2-4. If the DAQ device is connected to the SCXI-1503,these digital lines are unavailable for general-purpose digital I/O.Table 2-4. SCXI-1503 50-Pin Rear Connector SignalsPinSCXISignal NameNI-DAQmxDevice SignalName Direction Description1, 2 AI GND AI GND — Analog input ground—connects tothe analog input ground of the DAQdevice.3 AI 0 + AI 0 + Input Channel 0 positive—used todifferentially multiplex all16 channels, the CJ sensor, andanalog signals from the modules tothe connected DAQ device.4 AI 0 – AI 0 – Input Channel 0 negative—used todifferentially multiplex all16 channels, the CJ sensor, andanalog signals from the modules tothe connected DAQ device.24, 33 DIG GND D GND — Digital ground—these pins supplythe reference for E/M Series DAQdevice digital signals and areconnected to the module digitalground.25 SER DAT IN P0.0 Input Serial data in—this signal taps intothe SCXIbus MOSI line to sendserial input data to a module orSlot 0.
