Specifications

PICED FAQ

Page 39

Alternatively, logic code can be written to create delays between actions.

1.4.2.2 C-Bus Command Queue

Problem

Why does it take several seconds to execute a large Scene ?

Cause

Approximately 40 ON/OFF commands can be sent to C-Bus per second. If you have a large scene

with 120 Group Addresses, it will take up to 3 seconds to send all of these commands.

When C-Bus commands are sent by the PICED software (from Scenes, Schedules, logic and

button presses), the commands are placed in a queue, then sent out in order as fast as possible.

If you execute several scenes in quick succession, sometimes you can get unexpected results.

Consider the case where you set a scene which switches 120 Group Addresses ON, then

immediately set another Scene switching those same Group Address OFF again and then

immediately set the original Scene again. You will have 360 C-Bus commands in the queue which

will take around 9 seconds to be all transmitted to C-Bus. During those 9 seconds, you will see the

Group Addresses go ON, then OFF, then ON again. This is normal behaviour. During this time, if

you try to send other commands from PICED, these commands will also be added to the end of

the queue, so it will take a while for them to happen.

When a Scene is set, the Group Addresses on the PICED screen will show the new state

immediately to provide immediate feedback. There will be a brief discrepancy between the state

shown on the screen and the state on C-Bus.

If you set a large Scene and one of the Group Addresses has a short pulse, you may find that the

pulse duration is changed. Consider the case where you set a Scene with 120 Group Addresses

and the last one has a 2 second pulse. The 120 C-Bus commands get put in the command queue.

2 seconds later, the "falling edge" of the pulse is added to the queue. At this stage, the queue still

contains 40 commands. You will end up with the falling edge of the pulse being straight after the

rising edge of the pulse in the queue and so they will be sent out very close together in time.