Chapter 4 Hardware Overview

your NI 5102 and afterwards whenever operating environment conditions change.

Externally recalibrate the NI 5102 when its interval has expired. This requires connecting a precision reference to your device, and is normally performed at NI or a metrology lab. See Appendix A, Specifications, for more information about calibration intervals, and your NI 5102 Calibration Procedure for detailed external calibration instructions. This procedure is available at C:\VXIpnp\Win95\NISCOPE\Documents\ ni5102cal.pdf.

You may choose to write your own external calibration procedure in NI-SCOPE. Refer to your NI-SCOPE Software User Manual for more information about calibration.

RTSI Bus Trigger and Clock Lines

♦NI 5102 (PCI and ISA)

The RTSI bus (not available on the NI 5102 PCMCIA or USB) allows NI digitizers to synchronize timing and triggering on multiple devices. The RTSI bus has seven bidirectional trigger lines and one bidirectional clock signal.

You can program any of the seven trigger lines as inputs to provide

Start Trigger, Stop Trigger, Sample Clock and Board Clock signals sourced from a master device. Similarly, you can program a master NI 5102 to output its internal Start Trigger, Stop Trigger, Scan Clock, and Analog Trigger Circuit Output signals on any of the trigger lines, as shown in Figure 4-12.

Chapter 4 Hardware Overview

Figure 4-12. RTSI Bus Trigger Lines

The RTSI bus clock line is a special clock line on the RTSI bus that can only carry the timebase of the master to the slaves. For the smallest jitter between measurements on different devices, you should configure the slaves to use the RTSI bus clock from the master NI 5102.

♦NI 5102 (PXI)

The NI 5102 (PXI) uses the PXI Trigger <0..5> to carry RTSI Trigger <0..5> and uses PXI Trigger 7 to carry the RTSI clock signal to all other PXI slots in the system. RTSI Trigger 6 is reserved for use with PXI Star Trigger, which the NI 5102 can receive but may not drive.