The Grayson Master clock with one secondary clock line. The line can be configured for polarised pulses. Suitable for installations with up to, 80 secondary clocks.(80 Slave clocks). Convenient entry of the switching program via numeric keyboard. Automatic transfer of time and date from the connected radio time receiver (MSF), or GPS (option), 2 switching circuits are already built into the clock (make contacts) these can provide virtually unlimited possibilities for programming the channels, via the system with channel programs and week programs. Week programs specify how a channel has to behave with respect to hour, minutes, and weekdays. Channel programs specify in which operating period (date) which week program shall be executed. Software is available as an option that enables switching and signalling programs to be conveniently developed on a PC (off line) and then loaded in the master clock via a serial interface. The clear layout of the keyboard and display allow simple operation. Automatic transfer of time and date from the connected radio time receiver (MSF). Daylight saving time optionally automatic, controlled by radio receiver, or according to programmed changeover data. Versatile configuration possibilities, such as choice of type of line, with the possibility, of adjusting the pulse and pause times, and the operating mode of the secondary clocks (seconds, minute, or half-minute). Available as an option is a console for mounting the master clock with built in batteries for active back up. The case is of light plastic.