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[CAPL Functions](../../CAPLfunctions.md) » [MOST](../CAPLfunctionsMOSTOverview.md) » mostSetTxLight

# mostSetTxLight

[Valid for](../../../Shared/FeatureAvailability.md):  CANoe DE

**Note**

This functionality is available for:

* VN2600/VN2610/VN2640
* OptoLyzerOL3150o (firmware version >= V1.5.3)

## Function Syntax

`long mostSetTxLight(long channel, long txlight);`

## Description

Sets the Light Status at the Fiber Optical Transmitter (FOT).

## Parameters

* **channel**: Channel of the interface to be queried
* **txlight**:
  * `0`: disable FOT: Tx light off
  * `1`: enable FOT:
    * TimingMaster: Modulated light on
    * TimingSlave/Bypass: Tx light = Rx light
  * `2`: enable FOT: Constant light on (only available for VN2600/VN2610/VN2640/OptoLyzerOL3150o)
    * For OptoLyzerOL3150o: The stress network interface controller (NIC) must have its bypass opened (see [mostSetStressNodeParameter](CAPLfunctionMOSTSetGetStressNodeParameter.md)).

## Return Values

* `<0`: See [error codes](../CAPLfunctionsMOSTErrorCodes.md)

## Example

—

[mostGetRxLight](CAPLfunctionMOSTGetRxLight.md) • [mostGetTxLight](CAPLfunctionMOSTGetTxLight.md) • [mostSetTxLightPower](CAPLfunctionMOSTSetTxLightPower.md) • [mostGetChannel](CAPLfunctionMOSTGetChannel.md) • [OnMostTxLight](../EventProcedures/CAPLfunctionOnMOSTTXLight.md) • [mostShutDown](CAPLfunctionMOSTShutDown.md)
