Data Translation DT9837A User Manual

Contents

Data Translation DT9837A User Manual Manual pdf 71 page image

Principles of Operation71Single-Values OperationsIf you prefer to read a single value from all the analog input channels simultaneously usingone software call, use a single-values operation. You specify the analog input subsystem andthe gain that you want to use for the channels (not the channels themselves). The module thenacquires a value from each input channel simultaneously; the data is returned as an array ofinput values.Note: For the DT9837, a single values operation also returns a valid value from tachometercounter 0 (analog input channel 4), described on page 82.For the DT9837A and DT9837B, a single values operation returns values from the analoginput channels as well as from tachometer counter 0 (described on page 82), tachometercounter 1 (described on page 84), gate counter 2 (described on page 85), and the analogoutput readback channel (for the DT9837A; described on page 79), but only the data fromanalog input channels 0 through 3 is valid. Use continuous scan mode, described next, to readvalid data from the tachometer counters, gate counter, and analog output readback channel.For single-values operations, you cannot specify a clock source, trigger source, scan mode, orbuffer. Single-values operations stop automatically when finished; you cannot stop asingle-values operation.Continuous Scan ModeContinuous scan mode takes full advantage of the capabilities of the DT9837 Series modules.You can specify a channel list, clock source, start trigger, reference trigger, post-trigger scancount, and buffer using software.On the DT9837 module, you can enter up to 5 entries in the channel list, including four analoginput channels (A/D channel 0 to 3) and tachometer counter 0 (A/D channel 4), described onpage 82.On the DT9837A module, you can enter up to 8 entries in the channel list, including fouranalog input channels (A/D channels 0 to 3), tachometer counter 0 (A/D channel 4), describedon page 82, tachometer counter 1 (A/D channel 5), described on page 84, gate counter 2 (A/Dchannel 6), described on page 85, and the analog output readback value (A/D channel 7),described on page 79. Using software, specify the channels you want to sample in sequentialorder.On the DT9837B module, you can enter up to 7 entries in the channel list, including fouranalog input channels (A/D channels 0 to 3), tachometer counter 0 (A/D channel 4), describedon page 82, tachometer counter 1 (A/D channel 5), described on page 84, and gate counter 2(A/D channel 6), described on page 85. Using software, specify the channels you want tosample in sequential order.On the DT9837C module, you can enter up to 4 entries in the channel list (analog input 0 to 3).Using software, specify the channels you want to sample in sequential order.