Synchronization Pulses
The SIM provides the synchronization pulses at intervals of 250°s. The alarm mode is transmitted across the width of the sync. pulse. The duration of a sync. pulse in alarm status is approx. 2°s. Normally, the synchronization pulse lasts approx. 3°s.
The duration of a complete telegram can vary between 4.6 to 16°s.
On the basis of all the available information provided by the sensors, the bus master (SIM) must decide whether the satellites are to be set in the alarm mode.
When the alarm mode is set by the SIM, all the trigger circuits (B+) of the ISIS are placed on trigger standby.
To trigger a stage, two separate signals must always be transmitted on the byteflight. The high-side (B+) switch of the trigger circuit in the satellites is controlled via the alarm mode of the byteflight.
The low-side switch is controlled by the microprocessor in the satellites. On the basis of the transmitted telegrams with the sensor signals, the trigger algorithm recognizes when the low-side (ground) switch has to be closed.
The following graphic uses a trigger stage as an example to show signal paths necessary for triggering.