NV5/NV3.5 Troubleshooting Manual Detailed Circuit Descriptions
Page 2-2 Issue 3.2 2014-12-10
Digital inputs
RFI filtering is provided on all digital input lines to ensure transmitter operation is not interrupted
due to RF pick up on control lines. Opto-couplers buffer/isolate the external circuits and prevent
unwanted transients from affecting transmitter operation. The digital inputs on connector J24 are
shifted in through shift register IC U42. These values are then relayed to microcontroller U41 over
the SPI bus.
Digital outputs
Shift registers U63, U64 and U83, controlled by microcontroller U41 over the SPI bus, control the
status of the digital outputs applied to connector J23. Digital output logic levels are configured
through the AUI.
Analog outputs
Digital samples of the selected (or defaulted) analog outputs are applied to DACs U61 and U62 by
microcontroller U41 over the SPI bus. The analog outputs of DACs U61 and U62 are applied to
connector J24, via operational amplifiers U66:A through U66:D and U70:A through U70:D.
Remote interface PWB (NAPI115A)
See electrical schematic Figure SD-18.
The remote interface PWB (A2) performs the following functions:
• Provides an interface between the remote control/monitor facility and the transmitter.
• Provides momentary contact activation switches for each of the 24 digital inputs.
• Provides configurable status or alarm indicator LEDs for each of the 24 digital outputs.
Digital inputs
Up to 24 digital inputs can be connected to terminal blocks J7, J8, J9 and J10. You can define these
digital inputs using the advanced user interface (AUI). Each must provide a logic low input (0 V) in
its active state to the associated terminal of the remote interface PWB. Momentary switches S1 (
01)
through S24 (
24), which can be labelled according to their function, provide a means to locally
activate the digital inputs.
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