Abstract: A loop transmission system includes a plurality of micronodes and a central processor operative as a supervisory station linked by two loop transmission lines each capable of transmitting in either direction around the loop. The central processor is adapted to transmit, in alternative cycles in a first then in a second direction about the loop. Each micronode is adapted to respond in a direction opposite to the direction of the command transmission. The system is operative to provide alternative transmission paths in opposite directions around the loop such that if a fault occurs, the system retransmits the prior command in the opposite direction during a next cycle of operation. At most, a one cycle delay occurs, yet the system is inexpensive and easy to install.

Abstract: A security system is disclosed which utilizes plural remote terminals for controlling access at plural locations throughout a secured area or building. Each of these remote terminals is capable of independent functioning, and includes a memory for storing plural independent identification numbers which define the personnel who will be granted access. These numbers stored in the terminal memories may be different from terminal to terminal, or may be uniform throughout the system, and may be the same as a list stored at a central processing location. Thus, access may be limited to the same group of individuals regardless of whether it is provided by a central memory list or a remote memory list. The remote memories provide total memory flexibility, so that the deletion of identification numbers from the list does not reduce the memory size.

Abstract: A security system is disclosed which utilizes plural remote terminals for controlling access at plural locations throughout a secured area or building. Each of these remote terminals is capable of independent functioning, and includes a memory for storing plural independent identification numbers which define the personnel who will be granted access. These numbers stored in the terminal memories may be different from terminal to terminal, or may be uniform throughout the system, and may be the same as a list stored at a central processing location. Thus, access may be limited to the same group of individuals regardless of whether it is provided by a central memory list or a remote memory list. The remote memories provide total memory flexibility, so that the deletion of identification numbers from the list does not reduce the memory size.

Abstract: A security system in which access at remote locations is limited to personnel inserting in the system a coded data card, the data of which compares favorably with data stored in a memory. The memory data comprises a table which permits access to selected terminals by selected personnel at selected times. Programming access to the system for the purpose of altering data in the access authorization table is limited to individuals who insert a supervisor's card into the system, which card enables the logic required for altering the authorization table.

Abstract: A security system is disclosed which utilizes plural remote terminals for controlling access at plural locations throughout a secured area or building. Each of these remote terminals is capable of independent functioning, and includes a memory for storing plural independent identification numbers which define the personnel who will be granted access. These numbers stored in the terminal memories may be different from terminal to terminal, or may be uniform throughout the system, and may be the same as a list stored at a central processing location. Thus, access may be limited to the same group of individuals regardless of whether it is provided by a central memory list or a remote memory list. The remote memories provide total memory flexibility, so that the deletion of identification numbers from the list does not reduce the memory size.