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GFK-1527A Chapter 2 System Components 2-5
2
CPU Mode Switch
The CPU Mode switch selects the operating mode of the CPU:
RUN/ENABLED, RUN/DISABLED
,
or
STOP
. The CPU mode can also be controlled from the programmer. However, the CPU Mode
switch position restricts the ability of the programmer to put the CPU into certain modes, as shown
in the following table.
CPU Mode Switch Position Allowable Programmer
Mode Command
Run/Outputs Enabled Run/Enabled
Run/Disabled
Stop
Run/Outputs Disabled Run/Disabled
Stop
Stop Stop
Run/Outputs Enabled Mode
In this mode, the CPU executes all portions of the sweep normally.
Run/Outputs Disabled Mode
In this mode, the CPU executes all portions of the sweep normally, but physical outputs are held in
their default state and remain unchanged. Refer to Chapter 4 for important information about
Run/Disabled mode in a Hot Standby CPU Redundancy system.
Stop Mode
In Stop mode, the CPU communicates with the programmer and the devices connected to the serial
port, communicates with other communications modules such as the ethernet module, and recovers
faulted modules. Values in the I/O tables can be changed using the programming computer.
The STOP/IOSCAN mode
is not a valid mode
in a redundancy system. Refer to Chapter 4 for
detailed information.
Port 1
The RJ-11 connector provides an RS-232 compatible serial port.
Port 2
The 15-pin D-connector is an RS-485 compatible serial port.
Port 3
The 15-pin D-connector at the bottom of the module provides an RS-422/RS-485 serial port. For
applications requiring RS-232 communications, an RS-232 to RS-422 converter (IC690ACC900)
or RS-232 to RS422 miniconverter (IC690ACC901) is available.
Note
An RS-422 Isolated Repeater/RS-232 Converter (IC655CCM590) is available for
applications requiring ground isolation where a common ground cannot be
established between components.