Write
- Updated2025-07-30
- 3 minute(s) read
Writes an element to a Lossy Stream channel. If the channel is full, this endpoint either drops the oldest element in the channel to make room for this new element or discards this new element.

Inputs/Outputs
lossy behavior (drop oldest)
—
lossy behavior specifies how this endpoint writes data to a Lossy Stream channel when an element comes in. The default is drop oldest element.
element valid? (T)
—
element valid? specifies whether the element is valid. If TRUE, the endpoint records the element valid? flag. If FALSE, the endpoint ignores the value of element. The endpoint does nothing if both element valid? and last element? are FALSE. The default is TRUE.
element
—
element specifies the data to write to the channel.
last element? (F)
—
last element? specifies whether this is the last element that the endpoint writes to the channel. The default is FALSE. If TRUE, the endpoint marks the channel as closed and ignores further calls to write. The reader endpoint can continue reading data until the last element? output of the reader endpoint returns TRUE.
size (1)
—
size specifies the number of elements that the endpoint will write to the channel. The default is 1.
data lost?
—
data lost? returns TRUE if the channel was full when the endpoint performed this write operation.
count
—
count returns the number of elements in the channel after this endpoint updates the channel. Use this output to monitor the relative writing and reading speed of the channel endpoints and make adjustments, if necessary.
channel
—
channel is the channel wire that connects this endpoint to a reader endpoint. |
FPGA Module Details
The following details apply when you use this object in an FPGA VI.
| Single-Cycle Timed Loop | Not supported. |
| Usage | When used on FPGA, the size input has no default value and must be connected to a constant with a value greater than zero. For arrays, this endpoint supports only fixed-sized one-dimensional arrays of supported data types. This endpoint does not support variable-sized arrays even if the array resolves to a single size at compile time. This endpoint does not support LabVIEW classes. If you use this endpoint with the single-precision floating-point data type, refer to the following topics for resource use, latency, and single-cycle Timed Loop support implications. |
| Resources | This endpoint requires FPGA resources proportional to the number you specified in size. |
| Notes | A channel terminal of a non-reentrant subVI can be connected to only one channel. If a non-reentrant subVI is called from multiple locations, the channel wires connected to a given terminal must resolve to the same channel at compile time. |
lossy behavior (drop oldest)
—
element valid? (T)
—
element
—
size (1)
—
data lost?
—
count
—
channel
—