Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 16)

Installation
Chapter 2
2Ć4
Table 2.A
1775-KA Switch Settings
If this
switch: Is: Then
1 OPEN the PLC will switch over to backup whenever one of the
following fault conditions occurs:
1. The 1775-KA module tries to hold control of the PLC-3
backplane for more than 138 microseconds.
2. The 1775-KA module experiences a execution timeout of
more than 32 milliseconds
3. The 1775-KA module experiences an internal stack
overflow
4. The 1775-KA module experiences severe Data Highway
communication problems.
1 CLOSED the primary PLC-3 will not switch to backup when a fault occurs
with the 1775-KA module.
2 OPEN the 1775-KA module will disable is Data Highway port
whenever the primary PLC-3 controller becomes deactive. The
module will no longer be able to transmit or receivemessages
through its Data Highway port.
Also, setting switch 2 to open enables the backup operation
feature.
2 CLOSED the Data Highway port on the module will remain active if the
primary PLC-3 becomes deactive.
3 OPEN the module may be connected up to 7,000 cable feet away from
a 1771-KF, a 1771-KG, 1773-KA or another 1775-KA module.
In addition to setting switch 3 to the open position, you must
also set switch 2 to closed position. This makes pin 25 on the
RS-232-C port of the 1775-KA module active (refer to figures
2.8 to 2.10). Note that switch 3 must always be closed for
communication with an RS-232-C device other than a
1771-KF, 1771-KG, 1773-KA, or 1775-KA module.
3 CLOSED the MODEM INTERFACE port of the 1775-KA module may be
connected to a standard RS-232-C device that is located within
50 cable feet of the module.
4 OPEN Switch 4 is reserved for future use and should always be left
open.
Module Placement
After setting the thumbwheel switch, insert the module into any one of the
module slots in the PLC–3 processor chassis. Whenever you power–up
the processor, the module will receive power also.