Browse Prior Art Database

Controller Backup/ Data Logger

IP.com Disclosure Number: IPCOM000048653D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 84K

Publishing Venue

IBM

Related People

Sawtschenko, AP: AUTHOR [+2]

Abstract

This article describes a system having at least one primary controller, one or more secondary controllers and a number of terminals arranged in a loop configuration. The secondary controller can be online relative to the master controller, can serve as a backup controller if the master controller is out of service or can be completely bypassed, i.e., logically removed from the system.

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Controller Backup/ Data Logger

This article describes a system having at least one primary controller, one or more secondary controllers and a number of terminals arranged in a loop configuration. The secondary controller can be online relative to the master controller, can serve as a backup controller if the master controller is out of service or can be completely bypassed, i.e., logically removed from the system.

Fig. 1 shows the master controller 10 having a primary loop adapter (PLA) 12 which links master controller 10 and a secondary loop adapter (SLA) 14 in a secondary controller 16. Secondary controller 16 also includes a primary loop adapter 18 for providing a serial communications link to a number of terminals 20 arranged in a loop.

Fig. 2 shows the secondary and primary loop adapters 14 and 18, respectively, in greater detail. Signals from the master controller 10 are applied to a termination circuit on an analog card 22 before being directed through connectors RL, TC and RC to a deserializer 24 in the primary loop adapter. The deserialized or parallel data signals are applied to a logic unit 26 in the primary loop adapter before being converted to serial form by serializer 28 and applied to a driver in a second analog card 30. The signal path includes normally closed relay contacts 32 and 34, the functions of which will be discussed later. Signals received from the terminals are applied to the primary loop adapter at a termination section on analog card 30. Depending upon the mode of operation, these signals are either applied through connections Tc and Rc to a deserializer 36 in the secondary loop adapter or to the input of deserializer 24. Detailed circuit connections for different modes of operation are described later. Assuming the terminal signals are applied to deserializer 36, these signals are routed through a logic unit 38 before being reconverted to serial form in a serializer 40. The signals provided at the output of serializer 40 are applied to a driver section on analog card 22 before being sent to the master controller.

Normally closed relay contacts 42 and 44 are also provided in the terminal signal path. Finally, normally open relay contacts 46, 48, 50 and 52 are provided for reasons discussed later.

The connections shown with solid lines within the primary and secondary loop adapters remain unchanged regardless of whether the loop adapters are operating online or in a backup mode relative to the master controller. The connections shown as dotted lines are changed as a function of the mode of operation.

Online operation is described with reference to Fig. 3 where simplified views of the loop adapters are shown. The relay contacts have been omitted, the analog cards have been omitted, the serializers and deserializers are shown only as "S" and "D" blocks, respectively.

During operation in an online mode, signals from the master controller are routed directly to logic 26 which monitors the signal stream fo...