RflyUdpBigMode Block¶

Toolbox: RflySim Swarm

RflyUdpBigMode block

Overview¶

Summary: This block receives big-mode or waypoint data from an external program through a fixed UDP protocol and outputs up to 20 groups of four-dimensional data to Simulink.

RflyUdpBigMode is a UDP receive S-Function for big-mode control, task planning, and external host interaction. At simulation start, the block binds local UDP port 5005. It receives packets containing a header, packet ID, point count, waypoint data, and CRC32 checksum. When the packet passes validation, the data is converted into a single vector output and an ACK is sent back to the sender.

This block is suitable for scenarios where Python, C++, a large language model planner, or other external programs generate waypoint/mode control data, which is then consumed in Simulink for swarm control or path tracking.

Ports¶

Inputs¶

This block has no input ports.

Outputs¶

Port	Data type	Dimension	Description
`WaypointData`	`single`	`80x1`	Up to 20 groups of four values. Each group is output as `[x, y, z, yaw]`. If no valid packet is received, all output elements are set to `0`

The upstream sender may assign the first groups to lock, takeoff, Offboard, waypoint ID, or multi-UAV control quantities, and use the remaining groups as waypoint coordinates. The Simulink-side parser must use the same task-level convention as the sender.

Parameters¶

This block has no Mask parameters.

Communication Protocol¶

UDP Port¶

Item	Value
Local listen port	`5005`
Receive timeout	`5 ms`
Sample time	`1/30 s`
Maximum data groups	`20`

Packet Layout¶

Field	Type	Description
`header`	`uint16`	Fixed header `0xAA55`
`packet_id`	`uint16`	Packet ID used for ACK confirmation
`num_points`	`uint8`	Number of data groups in this packet. Values above 20 are truncated to 20 groups
`reserved`	`uint8`	Reserved field
`waypoints`	`Waypoint[num_points]`	Each group contains `double x`, `double y`, `float z`, and `float yaw`
`crc32`	`uint32`	CRC32 checksum of the header and data area

ACK Layout¶

Field	Type	Description
`header`	`uint16`	Fixed header `0xAA55`
`packet_id`	`uint16`	Confirmed packet ID
`status`	`uint8`	`0x01` means success, `0x02` means CRC failure
`reserved`	`uint8`	Reserved field

Block Characteristics¶

Item	Value
Block type	Level-2 C/C++ S-Function
S-Function name	`RflyUdpBigMode`
Number of input ports	`0`
Number of output ports	`1`
Output data type	`single`
Output width	`80`
Code generation support	No

Usage¶

Start the external program that sends big-mode or waypoint data.
Make sure it sends UDP packets to port 5005 on the Simulink host.
Connect the RflyUdpBigMode output to a custom data parser, waypoint controller, or swarm-control module.
Use the ACK status field on the sender side to check whether the packet was received and passed CRC validation.

Notes¶

Port usage: Only one process can bind UDP port 5005 on the same host. Close other programs occupying this port before starting.
Zero output: The block outputs only the last successfully validated packet. When no valid data is available, it outputs a zero vector. The downstream control logic should handle zero-input conditions.
CRC consistency: The sender must compute CRC32 over the header and waypoint data, excluding the trailing CRC field itself.
Task-level convention: The block only parses four-value groups. The meaning of each group must be agreed between the sender and Simulink parser.

Changelog¶

v4.10 (2026-05-07): Added the RflyUdpBigMode help document and connected it to the Simulink Help button index.