High Voltage D/A (Module J8)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 137 of 330HIGH VOLTAGE D/A (MODULE J8)Principle of OperationFour D/A channels are provided per module andinclude extensive diagnostics. The output datacommand word is formatted as a percentage of theFull Scale (FS) range selection which allows formaximum resolution and accuracy at lower voltageranges. Overloaded outputs will be detected, withthe results displayed in a status word. This moduleincorporates major diagnostic capabilities that offersubstantial improvements to system reliabilitybecause user is alerted to malfunctions within 500milliseconds.Built-In-Test (BIT) / DiagnosticCapabilityTwo different tests, one on-line (D2) and one off-line (D3) can be selected:The on-line (D2) test initiates automatic background BIT testing, where each channel is verified to a testaccuracy of 2% FS. Any failure triggers an Interrupt (if enabled) with the results available in status registers. Thetesting is totally transparent to the user, requires no external programming, has no effect on the operation of thiscard and can be enabled or disabled via the bus.The off-line (D3) test uses an internal A/D that measures all D/A channels while they remain connected to the I/O.Each channel will be checked to a test accuracy of 2% FS. The test cycle runs through nine output levels withinthe programmed range and polarity of the channel pair (@ 0.125% steps of FS). The test cycle is completedwithin 10 seconds and results can be read from the Bit Status register when (D3) test enable changes from “1” to“0”. The test can be stopped at any time. This test requires no user programming and can be enabled or disabledvia the bus.CAUTION: D/A Outputs are active during D3 test. Check connected loads for interaction. D/A Over-Current (short circuit) monitoring is disabled during D3 testing.Data (Write D/A) OutputIf using bi-polar mode, write 16 bit two’s complement word to the channel’s Data register (7FFFh=+FS, 8000h=-FS) If using uni-polar mode, write 16 bit binary word to the channel’s Data register (range: 0 to FFFFh=FS). Atpower-on, output is initialized to 0 volts.REGISTER D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 FUNCTIONDATA OUTPUT D D D D D D D D D D D D D D D D D=DATA BITMUXStateMachine14Wrap-AroundTestA/DDA 1DA 4ProtectiveCircuitsHigh Voltage DA Module Block Diagram41Module BusUser InterfaceCurrent LimitCircuit 1Current LimitCircuit 4MUX41
