61883 UNIT DEVICE DRIVER
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This command returns a handle for the specified plug. Any integer numbers can be used, or the following predefined constants:. If there were established isochronous connections before bus reset, the driver attempts to restore all connections as described in IEC and resume any active transfers that were in progress.
This command frees any resources associated with this handle, including the PCR. Applications should detect empty packets by comparing adjacent packets' continuity counters DBC field of the CIP header. The argument is a pointer to the structure: This command frees any resources associated with this handle.
This command stops an isochronous transfer. The following commands only apply to asynchronous nodes: See attributes 5 for descriptions of the following attributes:. There must be no active transfers and the data buffer must be unmapped; otherwise the command fails.
GET_UNIT_CAPABILITIES structure
Data rate expected by the AV device can be lower than the bus speed, in which case the driver has to periodically insert empty packets into the data stream to avoid device buffer overflows. Command fails if the plug already exists. Synchronization between user processes and the driver is performed using ioctl 2 commands.
The argument is a pointer to the structure:. Allowed values are from 0 to 3. Asynchronous data exchange between a driver and an application utilizes a common data structure called asynchronous request ARQ: Bus-specific overhead, such as isochronous packet headers, is handled by the driver and is not exposed to applications. On the local unit local plug.
Empty packets are not returned by read 2. This can happen when an application does not supply data fast enough. For the purposes of time stamping, the driver considers the first devjce in a frame buffer to be the first packet of an AV frame. An iec compliant driver exports two device nodes for isochronous and for asynchronous transactions. In other case these should be set to 0. When transmitting data, several bits can be set at a time, in which case the driver chooses one, for example, 0x3FF means a range from 0 to 9.
_GET_UNIT_CAPABILITIES - Windows driver | Microsoft Docs
Device and Network Interfaces. The data buffer is unlt into a user process address space, which means no data copying between the kernel and an application is necessary. This command returns current incoming ARQ buffer size. This Document Entire Library.
The plug should exist on the remote unit, otherwise the command fails. The argument is the new buffer size in bytes. Attributes See attributes 5 for descriptions of the following attributes: A driver and an application act as a producer and a consumer: Ioctls The following commands only apply to isochronous nodes: For both methods, if during transmit the driver runs out of data, it transmits empty packets containing only a CIP header of the next to be transmitted packet, as defined in IEC If no channels were allocated, the driver uses the broadcast channel by default and allocates the default-size data buffer.
Frames are numbered starting with zero and are always transferred sequentially.
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