Program Interface Library
AR_MODIFY_MSG
CEI-100/CEI-200/CEI-
x20 User’s Manual
114
AR_MODIFY_MSG
CEI_INT16 ar_modify_msg (CEI_INT16 board, CEI_INT16 channel,
CEI_INT16 msg_num, CEI_INT16 rate, CEI_INT32 data)
This routine modifies the data and transmission rate of a message being
scheduled by the ARINC interface. It is applicable only to Scheduled
transmission mode (see AR_MSG_CONTROL). It can only be called to
modify data for a message that has been defined with a previous call to
AR_DEFINE_MSG. Once a call to this subroutine is completed, all
subsequent scheduled transmissions will use the rate and data defined
here.
To disable a previously scheduled message, call this routine with a value
of zero for the rate argument. The message may be re-enabled later by
setting the rate argument to a non-zero value. If the new rate is the same as
the old rate, the label is re-activated in the same relative timing position,
relative to all of the other scheduled mode labels.
If you have a CEI-520/520A/620/820/820TX, the enhanced API supports
SIGNALED MESSAGES. In this mode, a specified ARINC receiver
looks for a specified label; the filter can be setup to look for any
combination of filtered bits as follows:
eSSM
SDI
label
Bits:
30, 29, 28
9, 8
7, 6, 5, 4, 3, 2, 1, 0
The values FILTER_SIGNAL and FILTER_CHANNEL are used to signal
a specific label previously setup by a call to AR_DEFINE_MSG(), and
enabled by a call to AR_MODIFY_MSG(), which will be transmitted by
the signaled transmit channel as soon as possible after the specified label
has been received.
To enable this mode first call AR_DEFINE_MSG() to create the ARINC
word that is to be transmitted when the desired label is received. When
you call this function use a negative
rate
. Then call AR_PUTFILTER() to
define the label that SIGNALS the transmit channel. You may wish to call
AR_GETFILTER() to read the current filter buffer, update the filter and
call AR_PUTFILTER() to write the result back to the board.
You can change the scheduled mode label that responds to the SIGNAL by
calling this function with the new “msg_num” and a negative rate.
Syntax
Description
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