Documentation Home Page RT-LAB Home Page
Pour la documentation en FRANÇAIS, utilisez l'outil de traduction de votre navigateur Chrome, Edge ou Safari. Voir un exemple.

OpAsync 429 Send




This block is part of the ARINC 429 library and is based on the AsynchronousProcess architecture. It is associated with a single OpAsync 429 Ctrlblock.

The OpAsync 429 Send block has two purposes:

  • allow the user to define the configuration of a specific send operation associated with a transmission channel
  • provide the ARINC words to be transmitted

The block provides access to the basic configuration elements of a single send operation for a given Label / SDI. More than one send block may be used for each channel.


Controller IDSee OpAsync429 Controller documentation.
Send IDEach OpAsync 429 Send block is assigned a unique SendID to be distinguished among multiple send blocks.
Sub-device numberOne ARINC 429 board can contain more than one independentARINC 429 capable devices. This parameter specifies which sub-device is to be used by the current block. The availability of the sub-devices depends on the ARINC 429 board model that is used.
Channel NumberThis parameter corresponds to the number of the channel that is to be used on the selected sub-device. It is important to note that, on a given sub-device, the reception channels must precede the transmission channels and that no channels may be used in both transmission and reception modes. This value ranges from 1 to 8.
Transmit SpeedSelect the transmission speed between 12.5k bps and 100kbps.
Operation ModeAllows selecting between the Legacy and Advanced operation modes. The following table describes each mode:

The data section of the ARINC word is provided on the Data input while the SSM, label, and SDI fields are provided either as block inputs or parameters.The complete ARINC word is provided on the Data input. The parity bit is ignored by the board if Parity control is enabled.
The block may be vectorized to transmit many ARINC words per step.The block may be vectorized to transmit many ARINC words per step.

LabelAvailable only in Legacy mode. The first 8 bits of the ARINCword, known as the Label, identifies the type of information contained in the 32-bit ARINC word. If the value entered exceeds 255, it returns to 0. The SDI can be used along with the Label in the ARINC word, in this case, the SDI value is automatically incorporated with the label value input in this box.
Use SDIAvailable only in Legacy mode. Checking this box enables the 2-bits SDI in the ARINC word.
SDIAvailable only in Legacy mode. The SDI is optional and when used, it occupies bits 9 and 10 of the ARINCword. The SDI adds an extension to the ARINC word's Label. ARINC systems are supposed to decode the Label/SDI combination as a different Label than an ARINC word with the same Label and no SDI implementation.
Sending mode

Specifies the relationship between the asynchronous program and this block:

  • NEED_REPLY_BEFORE_NEXT_SEND: When using this mode, the block needs confirmation that the data has been sent. The confirmation is only required at the next send request Confirmation is given by the asynchronous program by using the OpalAsyncSendRequestDone function from the RT-LAB Asynchronous Process library.
  • NEED_REPLY_NOW: When using this mode, the block needs confirmation that the data have already been sent. These modes cause the model to be stopped until the asynchronous program confirm that the data have been sent. (Confirmation is given by the asynchronous program by using the OpalAsyncSendRequestDone function from the RT-LABAsynchronous Process library).
  • DONT_NEED_REPLY: When using this mode, the block do not need any confirmation that the data have been sent.

Note: using either the NEED_REPLY_NOW or the NEED_REPLY_BEFORE_NEXT_SENDoptions may cause overruns if the model has to wait for a period that is longer or comparable to the step size duration.

Use Parity control: Allow control of the parity generation of the transmitted words. If this parameter is checked, the input 'Parity Control' is added to define if the parity is normal (=odd), even or disabled.


DataReadyThe block performs a transmission only when this input is 1.
DataIn Legacy mode, this input provides the 19 bits data field of the ARINC word. In Advanced mode, this input provides the complete 32 bits ARINC word, except for the parity bit, which is calculated by the board unless parity control is disabled.
SSMAvailable only in Legacy mode, this input provides the 2bits SSM field from the ARINC word.
Parity ControlAvailable only if the parameter Parity Control is checked. This input defines the parity type of the transmitted word, as explained in the table below.

Input valueDescription
0Even parity. This is the error parity of the board.
1Odd parity. This is the normal parity of the board.
2Parity control disabled. In Legacy mode, the parity bit is set to 0. In Advanced mode, the parity bit supplied in the input Data word is transmitted with no modification.

Please see the documentation of the block OpAsync_429_Recv to know the effects of the parity in the reception for SBS cards.


Error: Currently unused.

Characteristics and Limitations

Direct FeedthroughYes
Discrete sample timeYes
XHP supportNo
Work offlineNo

OPAL-RT TECHNOLOGIES, Inc. | 1751, rue Richardson, bureau 1060 | Montréal, Québec Canada H3K 1G6 | | +1 514-935-2323