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OpAsync 1553 RT_Recv block




This block is used to return messages received by a specific MIL-1553 Remote Terminal/ Sub Address. Only one instance of this block for each RT/SA couple is allowed.

This block is associated with one MIL-1553 card by the mean of the Controller ID parameter, which associates this block with an OpAsync1553_Ctrl block in the model.

The information about the RT/SA couple specified in this block is transferred to the Asynchronous Application in order to program the card for simulation of this RT/SA in receive mode. The data received by this RT/SA couple is transferred from the Asynchronous Application to the model via the shared memory opened during model initialization and returned at the Data outport of the block.

This block is not used for reception of Mode Commands. Use the OpAsync1553_Recv_ModeCommand block instead.
For more information MIL-1533 RT-LAB applications, check the RT-LAB MIL-1553 Manual.


Controller IDThis parameter retrieves to which Op1553_AsyncCtrl block the present block is associated. This ID is a literal integer value in the range [0, 255]. An Op1553_AsyncCtrl block with the same ControllerID value must exist in the model.
Receive IDThis parameter is used by the Asynchronous Process to differentiate between the OpAsync_1553_RT_Recv blocks attached to the same Op1553_AsyncCtrl block.
Sub-device numberSome MIL-1553 boards can support more than one MIL-1553 device. Each individual device is then referred to as one sub-device. This parameter is used to associate the current OpAsync_1553_RT_Enable block with one sub-device of the MIL-1553 card selected in the associated Op1553_AsyncCtrl (same ControllerID value). This parameter is grayed out if the card selected in the Op1553_AsyncCtrl block holds only one sub-device.
Remote TerminalIndicates the number of the Remote Terminal simulated by this block. This value is a literal integer value in the range [0, 30].
Sub-AddressIndicates the Sub-Address simulated by this block. This value is a literal integer value in the range [0, 31].
Enable Network Control for current RTDefines the current receive block as a network control block. Defining more than one network control block for a given RT and controller does not have any additional effect.
BroadcastIndicates the current Receive block has to be configured to receive all the broadcast messages for a given Sub-Address. The remote terminal number will then be automatically set to 31.
Firmware queue sizeThis value represents the number of slots in the firmware's circular queue that handles interrupts. Choose higher values when messages are expected to be received with little or no delay for the current RT/SA combination.
Maximum number of DWORDS per messageThis value must be large enough to accommodate the largest packet expected.
Number of reception buffers

The value given to this parameter indicates the number of messages that can be received during the same step. One message requires one buffer.

E.g. if the value is 3, there will be three buffers allocated in the Data signal. The length of these buffers is given by the maximum number of DWORDS per message.


Timeout: Currently unused. Set to 0.


This block has 5 outputs used to return values obtained from the MIL-1553 card by the Asynchronous Process.

  • Error: This output reports one of the following values:
0No errors.
-1An error occurred during initialization and the asynchronous process has terminated. Consult the RT-LAB Display for details.
-2An exception occurred. Please contact the Opal-RT support team should this be reported. Consult the RT-LAB Display for details.
-20The received packet contains more data words than the width of the Data output allows to produce. In this case, the exceeding data words are discarded, but Word Count still reports the actual message length.
  • Status: This output reports one of the following values:
0No new packets have been received.
1The asynchronous process is processing the reception.
2A new packet has been received and the Data and Word Count outputs have been updated.

Data: This output returns the data values received by the RT/SA specified in the parameters of the block. The width of this signal equals the maximum number of DWORDS per message times the number of reception buffers. I.e. if the maximum number of DWORDS is 32 and the number of buffers is 2 then the width of Data will be 64 where the first 32 elements are from the first buffer and the last 32 are from the second buffer.
Note that, because of hardware limitations, data associated with transmitted mode codes are not reported.

Word Count: Specifies the length of the received message. This value is set to -1 for the oldest messages. The width of this signal is the number of reception buffers.

Timestamp: This vector of 6 values indicates the timestamp of the message. The values are reported in this order: day, hours, minutes, seconds, milliseconds, and microseconds. This output is set only when the 'extended RT' mode is selected in the OpAsync_1553_Ctrl. Otherwise, they are set to 0. Note that if the MIL-1553 card does not have the IRIG-B option, only the 'microseconds' field is set. The width of this signal is 6 times the number of reception buffers.

OverflowThis output is set to 1 if during a step there were more messages received than what was configured. Otherwise, the value is set to 0.

Message count: This output is the total count of received messages. It can be used to validate how many messages are received by the model.

Characteristics and Limitations

The values returned at the Timestamp output are asynchronous to the model. If the device is not IRIG-capable, the timestamps returned are raw time values measured by the MIL-1553 board. Also, configuring the IRIG or device timer of the card is currently not supported.

Direct FeedthroughNo
Discrete sample timeNo
XHP supportNo
Work offlineNo

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