Transmission circuit of fire protection/security system

• US 4,847,593 A
• Filed: 09/15/1987
• Issued: 07/11/1989
• Est. Priority Date: 05/28/1986
• Status: Expired due to Term

• Current Assignee: Nohmi Bosai Kogyo Kabushiki Kaisha
• Original Assignee: Nohmi Bosai Kogyo Kabushiki Kaisha
• Inventors: Igarashi, Akira
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/110,759
• Time in Patent Office: 665 Days
• Field of Search: 340/518, 340/505, 340/825.06, 340/825.07-825.13, 340/506, 340/588, 340/589, 340/531
• US Class Current: 340/518
• CPC Class Codes: G08B 25/04 using a single signalling line, e.g. in a closed loop
• CPC Class Codes: G08B 26/002 only replying the state of the sensor
• CPC Class Codes: G08B 29/18 Prevention or correction of operating errors G08B29/02, G08B29/12 take precedence

Abstract

A transmission circuit is disposed in at least one of a control panel and a plurality of terminal devices of a fire protection/security system, wherein the control panel individually polls the terminal devices to read in terminal information from the terminal devices, to judge and/or display the information, or to control the terminal devices. The transmission circuit includes a signal sending device for sending a signal to a signal line, a memory device for storing a signal to be sent to the signal line, and a coincidence decision device for deciding a coincidence between the signal sent from the signal sending device and the signal stored in the memory device.

Claims

1. A transmission circuit, said transmission circuit disposed in at least one of a control panel and a plurality of terminal devices of a fire protection/security system, wherein said control panel individually polls said plurality of terminal devices, said transmission circuit comprising:

a signal sending means for sending a signal to be transmitted to a signal line;

a memory means for storing said signal to be transmitted;

a coincidence decision means, coupled to an output of said signal sending means and to said memory means, for comparing said signal to be transmitted sent from said signal sending means with said signal to be transmitted stored in said memory means.

2. A transmission circuit as claimed in claim 1, wherein said coincidence decision means comprises a means to stop a sending of a signal when said compared signals to be transmitted are not identical.