I/O Discrete (Module K7)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 188 of 330Input/Switch InterfaceThe channel contains a both an isolated differential amplifier and a dual N-Channel MOSFET, configured asisolated Solid State Relay (SSR). The channel can be configured ether for voltage measurement or switchclosure. In voltage mode, an isolated differential amplifier measures the voltage between the channels two I/Opins. When programmed as a switch the SSR is energized, and both AC and DC current can flow through thechannels I/O pins. The MOSFET presents a low ~.5 Ω on impedance. The K7 module contains circuitry tomeasure the current through the SSR and the voltage present on the I/O pins.Switch ControlEach individual channel may be programmed for either input or switch closed. When set to ‘1’ the I/O pin pair isconfigured as closed switch. Each bit corresponds to one of 16 channels (See Register Bit Map.)REGISTER D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 FUNCTION16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 ChannelSwitch Control D D D D D D D D D D D D D D D D D=DATA BITThreshold ProgrammingThere are four threshold levels (Max High, Upper, Lower, Min Low) together they offer maximum userprogramming flexibility. All four threshold levels must be programmed. The Threshold logic in the K7 modulemeasures the input RMS voltage value. The averaged RMS value is absolute value, and the threshold logic workswith DC or AC input voltages. The threshold programming values are represented as an unsigned binary.The threshold levels will define the logic states. For proper operation, the threshold values should be programmedwhere: Max High Threshold > Upper Threshold > Lower Threshold > Min Low Threshold.Program Upper and Lower Thresholds, keeping the 0.25V min. differential in mind, and then add de-bounce timeas required. When the input signal exceeds the Upper Threshold, logic level high “1” is maintained until the inputsignal falls below the Lower Threshold. Conversely, when the input signal falls below the Lower Threshold, logiclevel low “0” is maintained until the input signal rises above the Upper Threshold.Max High ThresholdUpper ThresholdLower ThresholdMin Low Threshold0.25 voltsWhen the input signalexceeds the UpperThreshold, a logic high “1”is maintained until theinput signal falls belowthe Lower Threshold.Conversely, the same istrue as the signalchanges from low to high,or high to low.Logic High “1”Upper ThresholdLower ThresholdLogic Low “0”Input SignalLogic State
