Preset for Two Edge Measurement under DAQmx

[Gary Armstrong]

Porting the Two Edge Measurement Counter from TDAQ to DAQmx is proving to be impossible. Apparently NI does not support loading a PRESET with the Two Edge Measurement Counter method under DAQmx. We have also tried the Event Counter method which does allow a PRESET but does provide a technique to route the CTR OUT to stop multiple counters.

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Executive Summary

This application utilizes multiple counters spread across multiple boards. The counters count neutrons except one counter that is dedicated to time. The counters need to start and stop at the same time. This is accomplished by connecting the start and stop lines to RTSI0 (start) and RTSI1 (stop). The start function (under TDAQ) is accomplished by toggling RTSI0 (see figure 1). The stop is accomplished by connecting the CTRn OUT from the (master counter) to the stop line. One of the counters is designated as the master counter (typically the clock). The master counter is loaded with a PRESET and configured to count down. When the master counter output line goes high, all counters on RTSI1 stop.

The TDAQ software permits two functions that I understand are going to go away when porting to DAQmx:

(1) The ability to toggle a RTSI line (for use as a global start/stop signal to all slave channels.

(2) Remote Device Access (RDA).

The in-ability to toggle a RTSI line in DAQmx means that a PCI-6602 channel (pulse generator) will have to be allocated to this task (a solution that HFIR scientist currently oppose, but is satisfactory for a temporary fix on GP SANs).

Test Two Edge Measurement.vi

Test Count Edges.vi