MULTIPLE INPUT UNIT will allow up to 12 separate sensors to be connected to the one Talking Display Unit (TDU-PRO). The TDU can then play one of up to 12 separate messages, held in its memory, depending on which sensor has been triggered. This means that : Sensor 1 when triggered will cause Message 1 to play Sensor 2 when triggered will cause Message 2 to play .....and so on up to sensor number 12. Sensors for use with the TDU need to be "normally closed" and also need to be modified with a current limiting modification. An optional in line current limiting adapter is available for those customers wishing to supply their own normally closed switches or sensors. Sensors can be located up to 100m from the TDU unit, or greater than 100m from the TDU if low resistance wiring is used. The remote sensors connect to the MIU via a female 25 pin D type connector. Each sensor has been allocated a specific pin position. While the TDU is playing a message, the MIU will continue to detect further triggering by the attached sensors and can hold in buffer up to 10 separate further triggers. Then when each message is complete, the MIU will instruct the TDU to play the message corresponding to the next triggering action. The TDU can only play one message at one time. Communication between the MIU and the TDU is achieved via a single 2 pair telephone cable, which is supplied with the MIU. There is no need for any other external connections.