Technical Bulletin

Communication Loss caused by Watchdog Timer Chip Supplied by Dallas Semiconductor

Advisory

Date

January 14, 2002

Reference

127

Route to

Service Manager/Modernization Manager

From

MCE Technical Support Department

Equipment

Any control or overlay system that is part of a group system and includes a computer swing panel with MC-CGP board(s). This excludes all programmable controllers, all simplex controllers, and all computer swing panels with an MC-CPA board.

Description

Through rigorous failure analysis, MCE has discovered that Dallas Semiconductor changed the characteristics of its Watchdog timer chip without notice. This chip is used on MCE's MC-CGP communication board.

Equipment shipped with MC-CGP boards between September 2000 and October 2001 may be affected. See detail below for type of equipment effected.
The problem will be seen as intermittent communication faults logged in the special events calendar as viewed on the F7 screen of the CRT. Faults will normally include one or more of the following:

• LOSS OF COMMUNICATION
• RS 422 NETWORK DOW
• CGP RESET
• SUBSYSTEM RESET

These communication faults may or may not affect the normal operation of the elevator system.

NOTE: These messages can, of course, occur for legitimate reasons and are not always the result of the above referenced problem.

Action

If you observe any of the faults described above, and you can not find a legitimate source of the event, please call MCE Technical Support for troubleshooting assistance. MCE will provide necessary replacement parts once the diagnosis has been confirmed.

Help

Should you require additional technical assistance:

• Telephone 916/463-9200
• Touch "6" for Technical Support
• Refer to the reference number above