1747-6.22, Backup Scanner User Manual

Module Control and Status Word 6-91
• Secondary System: This bit is set when the local system is in
the secondary state. If the primary bit is set, the secondary
system bit is not set. The reverse is also true. When the
secondary bit is set, the primary bit is not set. At powerup and
during switchover, these primary and secondary bits could be
reset at the same time;
• Number of 1747-BSN Modules: This bit indicates the number
of 1747-BSN modules in the system.
• Switchover Diagnostic: This bit is set when a 1747-BSN
module tests the functionality of the Remote I/O detector circuit
when the processor changes form Run to Program mode. If the
test fails, this bit is set until the next power down. In this case the
module must be replaced.
System Status Word Bits Number of 1747-BSN’s
11 10 9 8
0 0 0 0 1
0 0 0 1 2
0 0 1 0 3
0 0 1 1 4
0 1 0 0 5
0 1 0 1 6
0 1 1 0 7
0 1 1 1 8
Publication 1747-6.22