Multiplex communication system using remote microprocessors
First Claim
1. A communications system comprising:
- a local panel and a remote panel connected to the local panel by a communications line;
the remote panel including remote transmitting means for selectively transmitting a remote data signal at a first voltage level and a request signal at a second voltage level over said communications line to the local panel, the request signal being transmitted to request permission to subsequently transmit said remote data signal;
the local panel including local receiving means for receiving said remote data and request signals on said line, detector means for distinguishing the request signal from the remote data signal, and local transmitting means for transmitting a local data signal in response to the request signal;
the local data signal including a third voltage level; and
the remote panel including receiving means responsive to said third voltage level to cease transmitting said request signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A multiplex security system provides two-way data communications between a local panel and multiple microprocessor-based remote panels interconnected over a common data transmission line. A second line provides two-way voice communications between the local and remote panels with automatic forwarding by an audio/data control selector to a central control unit via a single telephone line. Two additional lines provide a common ground and transmit DC power from the local to the remote panels. The remote panels include bus drivers connected to the communications line for transmitting both ASCII digital data messages and a higher voltage request or SRQ signal to the local panel when the remote panel has a message to transmit. The local panel includes two separate receivers for distinguishing the request signal from digital data and a bus driver for transmitting data. The local panel transmits a grant message which is superimposed over the request signal, reducing its voltage level to zero. The remote panel has a receiver for receiving ASCII data from the local panel and for sensing the reduced voltage level to turn off the request signal. The remote panels are assigned priorities by setting different switch numbers in each panel. The switch numbers correspond to unique brief time slots in which each of the remote panels can commence transmitting. Following a grant command, the remote panels count time slots. None can respond until the count equals its respective switch number, and then only if another panel has not already commenced transmitting.
30 Citations
21 Claims
-
1. A communications system comprising:
-
a local panel and a remote panel connected to the local panel by a communications line; the remote panel including remote transmitting means for selectively transmitting a remote data signal at a first voltage level and a request signal at a second voltage level over said communications line to the local panel, the request signal being transmitted to request permission to subsequently transmit said remote data signal; the local panel including local receiving means for receiving said remote data and request signals on said line, detector means for distinguishing the request signal from the remote data signal, and local transmitting means for transmitting a local data signal in response to the request signal; the local data signal including a third voltage level; and the remote panel including receiving means responsive to said third voltage level to cease transmitting said request signal. - View Dependent Claims (2, 3, 4, 7, 8, 9)
-
-
5. A communications control system comprising,
multiple remote control panels interconnected by a common communications line, each panel being assigned a different numbered time slot in which to commence transmitting a remote data signal, and each panel including: -
counting means for counting time slots; transmitting means for transmitting remote data signals of a specified duration over said communications line; receiving means for receiving data signals on said communications line; and means for suppressing transmission if another panel commences transmitting while the count in said counting means is less than the number of its assigned time slot; the duration of each time slot being less than said specified duration. - View Dependent Claims (6)
-
-
10. A multiplex communications system comprising:
-
a local panel; up to N remote panels, N being an integer greater than one; a bi-directional data communications line connecting the local panel to each of the remote panels; a bus driver means in each of said local and remote panels for transmitting intermittent messages on said line; a bus receiver means in each of said local and remote panels for receiving data, including said messages, on said data line;
p1 remote signaling means in said remote panels for transmitting a remote signal different from said messages on said data line following one of said messages so that one of said remote panels can signal the local panel that it has a subsequent message to transmit;local receiving means in said local panel for receiving data, including said remote signal on said line; differentiation means in said local panel for distinguishing between said messages and said remote signal; reply means in said local panel responsive to said remote signal for transmitting an acknowledgment message via the local bus driver means on said data line; first disable means in each of said remote panels for terminating the transmission of said remote signals by said one remote panel and for suppressing subsequent transmission of another remote signal by any of said panels at least until completion of a message next following said acknowledgment message; counting means in each of said remote panels for counting up to N time intervals following said acknowledgment message; storage means for storing an identification number unique to each remote panel; first address comparing means in each of said remote panels for comparing the count in said counting means to said identification number to enable each of said remote panels to commence transmitting a message during a time interval corresponding to its identification number; second disable means in each of said remote panels responsive to commencement of transmission of a first message by one of said local and remote panels to suppress transmission of a second message by any different remote panel at least until said first message has ended; and third disable means in said local panel for suppressing the transmission of a second message until the later of the end of said first message and the end of said N time intervals. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
Specification