1747-6.22, Backup Scanner User Manual

1-40 Overview
Publication 1747-6.22
• REM RUN to REM TEST
• transfer of control from the primary processor to the secondary
when one of the following conditions is detected by the
secondary processor:
— communication timeout in the HSSL between the two
1747-BSN modules and primary system is not updating the
remote I/O
— transfer of control command from the primary 1747-BSN
module
• substitution of equipment without interruption of the process;
that is, the faulted system can be repaired while the other system
is controlling the process
• connections for remote I/O and Data Highway Plus network (the
1747-BSN module routes the remote I/O network and the Data
Highway Plus network to the primary processor)
• isolation of the systems, in order to guarantee that a fault in one
system does not affect the other
• diagnostics information
• remote programming capability for secondary processor. The
secondary processor is in the DH+ network
• the capability of switching two communication channels (one
configurable as RIO or DH+ and one RS-232/485 for DH485)
• minimal user programming impact
• use of standard SLC 5/02 or later and 1746 platform (no need for
special chassis or processor)
• no added cost if you are not using backup