Hit Crossing Probe — Control Systems/Messages And Events

Hit Crossing Probe

Control Systems / Messages And Events

Sends a message for every element of u that crosses, reaches or leaves an offset. With s the sign of u − offset (−1, 0 or +1) and s_p its value at the previous sample hit, an element whose s differs from s_p sends one message whose CrossingType names the pair: −+ 1, −0 2, 0+ 4, +− 8, +0 16, 0− 32. On the first sample an element sitting on the offset sends None (0), and one off it sends nothing. Leaving the offset in the direction it arrived from is not sent (0+ just after −0, 0− just after +0), so a one-sample touch is one crossing.

Ports

• Input u – the signal watched, any size [m,n]; every element is watched on its own.
• Output msg (msg) – a message line. Each message is a bus, R2026a's HitCrossMessage, of four elements: CrossingType (i32), the code above; Index (u32), the element that crossed, counted from 1 down the columns; Time, the sample hit; and Offset, the offset. Messages of one hit go out in element order. Read them with a Receive, whose value is then that bus.

Parameters

• Hit Crossing Offset – the offset, a scalar. Default 0.
• Hit Crossing Direction – which crossings are sent:
  • either (default) – every one, and the first sample’s None.
  • rising – −+, −0 and 0+.
  • falling – +−, +0 and 0−.
  The rule that drops a one-sample touch’s second half reads the previous crossing before this filter.
• Sampling Time (s) – zero or less inherits the solver's rate; a positive value runs the block at that period.

Code export

Python, MATLAB, Java, Rust, C and C++: the message line is one fixed-capacity queue in the generated core, and each crossing is pushed onto it as the bus’s four numbers, which the Receive at the other end turns back into the bus. The offset and the direction are inlined; the previous sign and crossing of every element are the block’s state, and Time is the block’s own clock.

VHDL, Verilog, SystemVerilog and PLC Structured Text refuse a message line by name: a hardware queue is left until a hardware design asks for one.

Simulink bridge

Import and export, mapped to simulink/Messages & Events/Hit Crossing Probe. Hit Crossing Offset ↔ HitCrossingOffset, Hit Crossing Direction ↔ HitCrossingDirection (either, rising, falling, one value for one value), and "Sampling Time (s)" ↔ SampleTime, as on every block. The export sets HitCrossingOutputType Message and ShowOutputPort on; a Discontinuities Hit Crossing whose HitCrossingOutputType is Message imports as this block. CrossingType is R2026a’s slHitCrossingType enumeration in Simulink and its int32 value here.

Notes

• Stateful: one previous sign and one previous crossing per element.
• Measured on R2026a, offset 0.25, either, at 0.1 s: u = 0.25 0.25 1 0.25 −1 0.25 0.25 1 sends None at 0, 0+ at 0.2, +0 at 0.3, −0 at 0.5 and 0+ at 0.7 – and nothing at 0.4, the second half of the touch at 0.3.
• Time is the sample hit, also under a continuous solver: R2026a reports the step after a crossing, not an interpolated instant, at a fixed step.