CTI Products CCU Channel Control Unit - Manual (Page 10)

CCU Hardware Reference Theory of Operation
CTI Products, Inc.
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3. Theory of Operation
The CCU contains 5 similar toggle sections:
Main / Standby Base Select
Repeat On/Off
Comparator A / Comparator B Select
Receive: Normal / Emergency Control Station (ECS) Select
Transmit: Normal / ECS Select
Each section is essentially a Toggle Flip-Flop with multiple inputs and outputs.
Depending upon the Option Switch setting, the 5 sections can operate
independently, or there may be some interaction between sections.
There is a sixth section that provides a Force Select output for a TSAM unit.
3.1 Toggle Section Overview
Each of the toggle sections has (3) toggle inputs, (2) "Normal" outputs and (2)
"Inverted" outputs. Normal and inverted outputs are available to drive the console
inputs to allow flexibility in implementation. In most sections, one of the Inverted
outputs will be used as feedback to the console, since it is active in the "abnormal"
condition (Such as Standby, Repeat Disable, ECS, etc.).
Refer to Figure 3 – Main / Standby Base Section Logic for details of a typical
toggle section.
The Toggle inputs are active low. The Flip-Flop will toggle when either input
makes a high to low transition (after a debounce time).
The debounce is followed by a one-shot, and only the leading edge (high to low)
transition is seen from the console. Thus a stuck Toggle output from the console
will not prevent the other console from toggling the function in the CCU.
Outputs are active low. The Normal outputs are active on power-up
Typically, the #1 outputs drive the system control units and the #2 outputs provide
feedback to the consoles.
Status bits provide feedback to PCs on the MCN network. Depending upon the
Display Table used for the particular function, the state of the output(s) and / or
the input(s) can be seen.
Control bits provide input from PCs on the MCN network. Depending upon the
Display Table used for the particular function, the operator may either toggle the
function or explicitly Set or Reset the function.