Discrete/Analog to Digital Combination (Module KA)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 199 of 330DISCRETE/ANALOG TO DIGITAL COMBINATION (MODULE KA)Principle of OperationDiscrete I/ODiscrete channels are programmable for Input or Output, Input only or Output only (see specification). Whenprogrammed or designated for Input, they can be used for voltage sensing. When programmed or designated forOutput, each channel is set for Lo-side (sink) operation. The Modules include diode clamping (available whenexternal VCC source is applied to DT-VCC pin) (which is useful for inductive loads, such as relays) and thermalprotection. Discrete I/O signals are referenced to power/system GND.Analog to Digital Conversion (A/D)Four (multiplexed) A/D channels are provided featuring one precision 14-bit A/D converter. The A/D converter hasan effective 3 KHz sampling rate per channel. The input range is field programmable for each channel. The abilityto set a lower voltage for Full Scale Input assures the utilization of the full resolution. All A/D channels are self-aligning. Each channel, on a rotating basis, is automatically aligned to eliminate offset and gain errors during theentire operating envelope. A/D single-ended signal returns are common and referenced to the A/D GND pin.Built-In Test (BIT) / Diagnostic CapabilityThe modules are incorporated with background BIT (A/D and/or Discrete I/O) which is always enabled andcontinually checks that each channel is functional. Background BIT functions during normal operations, isautonomous, transparent and requires no user “intervention”.Analog to Digital Conversion (A/D)This capability is accomplished by an additional “AD Test A/D” that is incorporated into each module. The AD TestA/D is sequentially connected across each channel and compared against the operational channel. Both the “on-line” and “Test A/D” must agree (within 0.2% FSR tolerance) otherwise a BIT fault will be set.Discrete I/OThis capability is accomplished by an additional “IO Test A/D” that is incorporated into each module. Fourthreshold levels (Max High, Upper, Lower, Min Low) are provided/programmed to user defined high and lowvoltage levels. All four threshold levels must be set for each Input or Output channel to validate BIT testing.Depending upon the channel/IO configuration, the Input data read or Output logic write (command) of theoperational channel and the IO Test A/D (which measures actual voltage potential at the I/O pin w/ reference tosystem GND) must agree or a fault is indicated with the results available in the associated status register. Note:As outputs (low side drive), when the channel is in the “off” position, no internal pull-up or automatic status maskis provided – either external pull-up must be utilized or appropriate operational software BIT mask must beinstituted for handling possible erroneous faults that may be flagged due to “floating” I/O-pin conditions.Additional testing is provided to check for the over-current condition. Testing is totally transparent to the user,requires no external programming, and has no effect on the standard operation of this card. Associated statusregister(s) can be checked or polled at any given time. Enable Interrupts, within any interrupt enable register, bysetting the appropriate channel bits to “1”.
