A pullsed bell output for fire on the D8112 is dependant on what is programmed into item #75 PULSE. It is a yes or no value. To begin, the fire circuit's zone code should be programmed as a 3181. This code gives the standard fire response of trouble on an open circuit, instant alarm on a short circuit, and restoral reports.
Assuming there is a D136 relay inserted in socket K6 to activate terminal 7 (Alternate Alarm output) The following will occcur...
If Item #75 PULSE is programmed as a YES, a fire alarm will create a pulsing 12vdc output in terminal 6 (Main Bell Output) and a steady 12vdc output at terminal 7. On a non fire alarm, Terminal 6 will produce a steady output, terminal 7 will produce no output.
If Item #75 PULSE is programmed as a NO, a Fire alarm will cause no output on terminal 6, and a steady output on terminal 7. On a non fire alarm, terminal 6 will provide a steady output, terminal 7 will supply no output.
Terminal 6 is the only output that can be made to pulse. Terminal 7 will always produce a steady output on a fire alarm, regardless of wether Item #75 PULSE is programmed as a Yes or a No.