Hardware reference guide

CPU Modules
35013379 11/2011 159
The following table shows the key switch information.
Modbus Connector Pinouts
All Quantum CPUs are equipped with a nine-pin RS-232C connector that support
Modicon’s proprietary Modbus communication protocol. The following is the Modbus
port pinout connections for nine-pin and 25-pin connections.
NOTE: Although the Modbus ports electrically support existing Modbus cables, it is
recommended that a Modbus programming cable (Part # 990NAA26320 or
990NAA26350) be used. This cable has been designed to fit under the door of a
Quantum CPU or NOM module.
Key Switch Description
Key switch
Position
Controller Status Memory
Protected
From
Programmer
Changes
Will Accept
Programmer
Stop or Start
Key switch
Transition
Stop Controller is stopped
and disables
Programmer changes.
Y N From Start or
Memory Protect:
Stops controller, if
running, and
disables
Programmer
changes
Mem Prt Controller may be
either stopped or
running and
Programmer changes
are disabled. User
cannot write to
unlocated variables.
Y N From Stop or Start:
Prevents
Programmer
changes,
controller run
status is not
changed
Start Controller may be
either stopped or
running. Programmer
may make changes
and start/stop the
controller
N Y From Stop:
Enables
Programmer
changes, starts
controller.
From Memory
Protect: Enables
programmer
changes, starts
controller if
stopped.