NV5/NV3.5 Troubleshooting Manual Reading Electrical Schematics
Page 5-2 Issue 3.2 2014-12-10
Unique symbols
Nautel uses unique symbols on electrical schematics to describe logic (two-state) signals. These
signals differ from single-state signals or analog signals that may have multiple values.
Type of inputs and outputs
On electrical schematics, names used to describe logic (two-state) input and output signals are
prefixed with a # symbol.
Logic level convention
The # prefix identifies an input or output signal that has two distinct states: high and low.
The suffix on an input or output signal name identifies the active (true) state of the signal. The high
suffix (+) indicates the more positive of the two levels used to represent the logic states. The low suffix
(-) indicates the less positive of the two levels.
Two types of logic, positive and negative, may be represented on a particular schematic. In positive
logic,
high represents the active (true) state, and low represents the inactive (false) state. In negative
logic, low represents the active (true) state, and high represents the inactive (false) state.
Identifying schematic diagrams
Each electrical schematic in this section is identified by a number that is both the figure number and
the page number. The numbers are assigned sequentially are prefixed by the letters SD. The electrical
schematics and logic diagrams included in this section are listed in Table 5.1 on page 5-5.
Structure of schematics
The electrical schematics are structured in a hierarchical format that is based on function and signal
flow. Wherever practical, the signal flow is from left to right. Normally, inputs originate on the left-
hand side and outputs extend to the right-hand side. Exceptions are shown by an arrow indicating the
direction of signal flow.
Note: The physical location of a part or assembly was not necessarily a factor during creation of the
schematic. The full reference designation assigned to a part or assembly, in conjunction with the family
tree (see Section 3, “Parts Lists” on page 3-1) and the assembly detail drawings (see Section
6, “Mechanical Drawings” on page 6-1), will identify its location.
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