ProSoft Technology AN-X-MOD - Manual (Page 44)

Page 40 AN-X-MOD (Master) November 2011
Redundancy
Controller Redundancy
For redundant controller applications, use the ControlLogix 1756-RM
redundancy modules.
They can also be used with two AN-X modules in redundant scanner
applications.
Scanner Redundancy
Version 2.2.1 and above of the firmware for the AN-X-MOD (Master)
includes features to implement redundant I/O scanners using two
AN-X-MOD modules.
One AN-X is designated the primary and acts as the scanner; the other is
designated the secondary and acts as a backup.
If the primary AN-X goes offline, the backup takes over.
The backup AN-X constantly monitors the S908 network. When it
becomes the primary, it has the current state of inputs, drop status, etc.
Each ControlLogix processor has access to current I/O data from the
S908 network.
The backup AN-X listens to the S908 network and waits for 10 ms of
silence on the network before it takes over. It does not start scanning if it
hears another master already online.
The ControlLogix configuration file must be modified to support
redundancy. No changes are required to the S908 I/O Configuration file.
Cabling
Using the Modicon Redundancy Terminator Kit
You can use the Modicon Redundancy Terminator Kit to connect to the
S908 network.
The AN-X module has built-in termination. Do not use the inline
terminators in the cable from the AN-X module to the splitter from the
kit.
Do not disconnect either AN-X module from the splitter since that also
removes the termination.