18 The
menus
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Checksum mode
Checksum mode displays the calculated checksum for the last packet received.
Both the 8 bit and 16 bit versions of the checksum are calculated. This provides a useful
check of data integrity.
If the transmitting device (console) is sending non-changing data, the checksums should
show a constant value. In this scenario, if the checksum is seen to change, data corruption of
the DMX signal is occurring. The checksum is displayed in hexadecimal format.
The checksum displayed relates to last packet received with a zero start code. i.e. the Start
Code selected in the setup menu is not used in this display. NB. The DMX512-A checksum
implementation has not yet been ratified by ESTA.
Trigger output
The spare two pins of the DMX512 output are used to provide a TTL (5V) oscilloscope
trigger output. This signal can be used to synchronies the oscilloscope to either the falling
edge of the break or the DMX base address.
45.2uS
52.8uS
TRIGGER
RRRRRR
DMX512
BREAK
Start bit goes low
DIMMER n
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