Interrogation device

Claim 2

An interrogation unit for connecting into an installation via sensing elements connected to sense required information in the installation, said interrogation unit having signal supplying means for supplying signals indicative of the condition of each of various sensors in the installation, and trigger circuit means activatable upon recipt of a request signal to transmit said signals for each of the sensors in turn, said signal supplying means including tone generating means which generates two different tones and being connected to either transmit said tones or not to transmit said tones, whereby to indicate that any particular sensor has changed from its initial condition or not, a first of said tones being used for identifying a group of sensors whilst the second of said tones being used for identifying particular sensors in that group.

Claim 3

An interrogation unit as claimed in claim 1 and including a respective latch circuit means associated with the connections for each of the sensors, whereby a user can optionally select to utilize a latch facility or not, said latch circuit means recording a change in the condition of a sensor, so that upon interrogation of the unit a signal will be transmitted representative of the respective sensor having changed from an original condition even if it has returned to the original condition.

Claim 4

An interrogation unit as claimed in claim 1 and including an alarm circuit for each sensor whereby a user can optionally select to utilize an alarm facility or not, said alarm circuit being for automatically initiating an alarm if a respective sensor changes from its initial condition independently of the unit receiving a request signal.

Claim 5

An interrogation unit as claimed in claim 1 and including visual indicator means for each sensor to visually indicate that said sensors have changed from their initial condition.

Claim 6

An interrogation unit as claimed in claim 4 including memory means for storing an initial condition of each sensor upon switching ON of said interrogation unit, thereby providing when accessed by a memory recall thereof, an indication of the original condition of sensors by causing said visual indicators to then indicate the original condition.

Claim 7

An interrogation unit as claimed in claim 1 including a microprocessor device for operation of said unit and programmed to scan sensors and to provide regularly updated information as to the condition of said sensors, said microprocessor being programmed whereby to transmit said signals in a sequential manner following said device receiving said request signal and to discontinue transmission of said signals after they have been transmitted a predetermined number of times.

Claim 8

An interrogation unit as claimed in claim 1 and connected with sensors in an installation.

Claim 9

An interrogation unit as claimed in claim 6 whereby to provide interrogation of said sensors by a telephone call providing said request signal.

Claim 10

An interrogation unit for connecting into an installation via sensing elements connected to sense required information in the installation, said interrogation unit having signal supplying means for supplying signals indicative of the condition of each of various sensors in the installation, and trigger circuit means activatable upon receipt of a request signal to transmit said signals for each of the sensors in turn, wherein said signal supplying means include tone generating means which is connected to either transmit said tone or not to transmit said tone, whereby to indicate that any particular sensor has changed from its initial condition or not, and wherein said tone generating means generates two different tones, a first of said tones being used for identifying a group of sensors whilst the second of said tones being used for identifying particular sensors in that group, said signal supplying means providing N bursts of said second of said tone signals for sensor N, and N+1 bursts for sensor N+1, whereby to identify sensors in the transmission by counting the number of tone bursts.

Claim 11

An interrogation unit for connecting into an installation via sensing elements connected to sense required information in the installation, said interrogation unit having signal supplying means for supplying signals indicative of the condition of each of various sensors in the installation, and trigger circuit means activatable upon receipt of a request signal to transmit said signals for each of the sensors in turn, wherein said signal supplying means include tone generating means which is connected to either transmit said tone or not to transmit said tone, whereby to indicate that any particular sensor has changed from its initial condition or not, and wherein said tone generating means generates two different tones, a first of said tones being used for identifying a group of sensors whilst the second of said tones being used for identifying particular sensors in that group, said signal supplying means providing N bursts of said second of said tone signals for sensor N, and N+1 bursts for sensor N+1, whereby to identify sensors in the transmission by counting the number of tone bursts.

Claim 12

An interrogation unit as claimed in claim 9 wherein said signal supplying means providing N bursts of said first of said tone signals for group N, and N+1 bursts fro group N+1, whereby to identify groups in the transmission by counting the number of tone bursts.