Model 5601ACO2 Automatic Changeover Unit
OPERATION Revision 1.2 Page 3-7
When DIP switch 8 and DIP switch 7 are in the Off position, the 5601ACO2 may change an unlimited
number of times depending on inputs when in automatic mode. When DIP switch 7 is in the On
position and DIP switch 8 is in the off position, and in automatic mode, only 1 change will be allowed if
they occur within 0.5 seconds. When DIP switch 8 is in the On position, and in automatic mode, only 2
changes will be allowed if they occur within 0.5 seconds. After this, the LEDs beside the switches will
flash. Moving any of the 3 switches or changing ACO GPI1 or ACO GPI2 will re-enable the
5601ACO2. This is provided to prevent back and forth toggling if an output is shorted out.
CAUTION: When DIP switch 8 is ON, the 5601ACO2 will not change over after a
quick change has happened. User input is needed to allow automatic changes
to happen again. It is important to promptly fix the offending input, and re-
enable the 5601ACO2 to ensure correct automatic protection.
3.4. GPO TALLY OUTPUTS
There are two general purpose outputs that can be used to signal alarm conditions to the user. These
outputs are driven by normally closed relays inside the 5601ACO2. When the relay is energized
(active), the output will be pulled to +5 volts by a 10 K ohm pull-up. When the relay is de-energized
(normal) the relay contact will connect the output to ground. See Figure
2-4 for a schematic of the
GPO output circuitry.
GPO1 is used to indicate whether Master A or Master B is currently selected. It will be low when
Master A is selected and high when Master B is selected.
GPO2 is used to indicate whether the Master A and Master B inputs are identical and the power
supplies are functioning correctly or not. It will be high when the inputs are identical and the power
supplies are good, and will be low when the inputs are not identical, or one or both of the power
supplies is not functioning correctly.
The default condition of the 5601ACO2 outputs when there is no power applied is that the Master that
was last active will be selected, and will be indicated by the GPO1 relay. GPO2 will be high impedance.
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