Part 2

EXAMPLE 4FAST SCAN VOLTAGEMEASUREMENTSExample 3497A Configurations 57 1DESCRIPTIONA useful application for the 3497A is high-speed voltage measurements on sequentialchannels. In this example, we'll show how to use the 3497A to scan 60 channelsat an approximate 125 channellsecond rate and store the measured DC voltages inthe -hp- 85 for future printout. With this method, you can take nearly simultaneousmeasurements of up to 60 channel inputs.PROCEDUREFor this example, we'll assume that a DC voltage source is connected to each ofchannels 0-59 (Option 010 assemblies in slots 0, 1 and 2) and that it is requiredto sequentially scan all 60 channel inputs after the occurrence of a specified systemevent, such as a switch closure.To initiate the 60 readings, connect an external input capable of generating a highto-lowTTL pulse to the EXT TRlG port. When the specified event (switch closure)occurs, the TTL pulse to the EXT TRlG port causes the DVM to take and store areading from each of the 60 channels. After all 60 readings are stored in the 3497A,they are transferred to the controller for printout.To indicate speed of measurement for different 3497A resolutions, the chart showsthe approximate time required to make a measurement with 3%, 4% and 5% digitresolution. The times shown are times to make the measurements and do not includetransfer time to the controller.Thus, for example, with 3% digit resolution about 8 ms is required to measure eachchannel (a 125 channellsecond measurement rate) so less than a half second is requiredto scan 60 channels (the maximum number of ASCII readings which can bestored).Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com