ARINC 429/575 Six Channel, Tx/Rx (Module A4)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 53 of 330Schedule Transmit CommandsREGISTER D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 FUNCTIONTX SCHEDULEMEMORY 0 0 0 0 X X X X X X X X X X X X STOP CMD0 0 0 1 X X X X MA7 MA6 MA5 MA4 MA3 MA2 MA1 MA0 MESSAGE CMD10 0 1 0 X X X X MA7 MA6 MA5 MA4 MA3 MA2 MA1 MA0 GAP CMD10 0 1 1 X X X X MA7 MA6 MA5 MA4 MA3 MA2 MA1 MA0 FIXEDGAP CMD10 1 0 0 X X X X X X X X X X X X PAUSE CMD0 1 0 1 X X X X X X X X X X X X SCH INTERRUPT CMD0 1 1 0 X X X SA8 SA7 SA6 SA5 SA4 SA3 SA2 SA1 SA0 JUMP CMD2Note 1: MA7-MA0 = Address of ARINC data word or gap time in Tx Message memory (organized as 256x32).Note 2: SA8-SA0 = Address of next command in Tx Schedule memory (organized as 512x16) to execute.Schedule mode begins execution at Schedule memory address 000h.MessageThis command points to a location in Transmit Message memory which contains the actual ARINC data word tobe sent. The word is transmitted when the next Message, Gap, or Fixed-gap command is executed. The ARINCword in Tx Message memory can be updated while the schedule is running.GapThis command points to a location in Transmit Message memory which contains a 20 bit number that specifiesthe gap time in bits to wait. Values less than 4 are invalid. If the previous command was Message, then thatmessage is transmitted and then the transmitter waits out the specified gap time transmitting nulls. An exceptionto this is if there is an async data word available. If the gap time is greater or equal to 40 bit times (4-bit gap timeplus one ARINC word plus another 4-bit gap time) then the following occurs. The message appended with a 4 bitgap time is transmitted, and then the async data word is transmitted. If a new async data word is made availableand the remaining gap time is large enough to accommodate another async data word transmission then the newasync data word will be transmitted after a 4-bit gap time. Multiple async data word transmissions can thus occuras long as the remaining gap time is large enough to accommodate a message and the required minimum 4-bitgap time. Otherwise, the transmitter waits out the remaining gap time before executing the next command.If the previous command was not Message, then the transmitter waits the specified gap time before executing thenext command. However, if there is an async data word available and the remaining gap time is greater or equalto 40 bit times (4 bit gap time plus one ARINC word plus another 4 bit gap time) then the following occurs. Theasync data word appended with a 4 bit gap time is transmitted. If a new async data word is made available andthe remaining gap time is large enough to accommodate another async data word transmission then the newasync data word will be transmitted after a 4 bit gap time. Multiple async data word transmissions can thus occuras long as the remaining gap time is large enough to accommodate a message and the required minimum 4 bitgap time. Otherwise, the transmitter waits out the remaining gap time before executing the next command.FixedGapThis command points to a location in Transmit Message memory which contains a 20-bit number that specifiesthe gap time in bits to wait. Values less than 4 are invalid. If the previous command was Message, then thatmessage is transmitted with the specified gap time appended. If the previous command was not Message, thenthe transmitter waits the specified gap time before executing the next command. The difference between theFixedGap and Gap command is that FixedGap will prevent the transmission of async data words during the gaptime. Use FixedGap to only allow nulls to be transmitted during the gap time.PauseThis command causes the transmitter to pause execution of the schedule after transmitting the current word.Either a Transmit Trigger command is issued to resume execution or a Transmit Stop command is issued to haltexecution.
