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C578M-A (4/05) 33
Figure A4-1 also highlight the two major differences between the current and previous hot switch:
1. COM Port Flexibility
The COM 1 and COM 2 Destination ports for the previous hot switch allowed for the connection
of the PC w/MGR and, if desired, an ASCII Control Device interfaced via a Pelco DT, for
example. The same relationship can be repeated in the current HS via the COM 1 and COM 2
Destination ports (located on the CPS) for the devices just mentioned, which are shown in
Figure A4-1. Note that COM 1 is usually reserved for the connection of the PC w/MGR in the
current HS. What is new is that the current HS allows an alternate choice (RS-232 instead of
RS-422) for the Data Line connection between the Source COM ports and the CC1 (A & B) DB9
ports located in the CCC. This choice was not available for the previous hot switch.
If you make this choice, however, the COM 2 (DT) Destination connection located on the CPS
and shown in Figure A4-1 cannot be used. This is because one of the Source COM ports must
be available for the connection of the PC w/MGR. The choices available for COM 2 port use are
covered in Figure 1-6.
2. Sercom Port Expansion
Six more SEUs (in addition to the two referenced in Figure A4-1) can be added by simply
connecting them to the hot switch common bus. This generously allows for any future expansion
of Sercom port use.
APPENDIX 4.3 HS UPDATE (Current Model Hot Switch Installed)
The steps described in Table E of the manual contain the general procedure to follow when updating
the hardware and/or software of an existing hot switch configuration. The following comments
supplement the information found there:
1. The “NOTE” located at the end of Table E identifies the steps in the table to follow as a general
procedure in case of a failure of one or the other CC1.
2. Be mindful of the considerations raised in Appendix 4.1. Is the node environment changing from
single to multi-node? Are other equipment changes being made that affect configuration files or
equipment cabling?
3. Once satisfied that the impact of all changes are accounted for, then the side under repair or
update can be powered up.
4. It should be noted that it is possible to update one side of a hot switch configuration at a time
without bringing the entire system down.