AIDA USDT Component

The USDT component implements the transport protocol ISO/WD 15765 (Unacknowledged Segmented Data Transfer or USDT). Most of the parameters are named in accordance with ISO/WD 15765 and are not described in further detail here. For any unknown/undescribed terms please refer to ISO/WD 15765.

Parameters

WFTmax

Specifies the maximum allowed number of consecutive FC.WAIT frames before the communication is stopped. When this value is set to 0 the maximum allowed number of consecutive FC.WAIT frames is not limited so there is a risk that the communication may hang completely.

STmin

The minimum time (in ms) between two consecutive CF frames.

BSmax

The maximum number of consecutive CF frames before a FC frame is expected. The value 0 has a special meaning: In this case all CF frames are sent without further handshake.

TXSTmin

This parameter can be used to override the STmin value passed by the communication partner. By default this parameter is set to -1 meaning that the value passed by the communication partner is used. If set to a value in the range from -255..-2 -TXSTmin is used as the lower limit in [ms] for the STmin value passed by the communication partner. If set to a value within the range from 0..255 the USDT component ignores the transferred STmin value and uses TXSTmin (given in [ms]) instead.
Note: Since the parameter is used as a workaround it will not be saved in a stack configuration when set to its default value.

PaddingByte

This parameter defines which value is used as padding value when filling up short messages to the configured length. The value -1 turns on an optimisation feature: The latest ISO/WD15765 specification allows the sender to send messages with the minimum length required to store all data. This especially affects SF and FC messages and the last CF message of a sequence. Note that it is optional on the sender side to implement this feature which means the receiver of these messages must accept both, full length and shortened messages. If it does not its ISO/WD15765 implementation is broken.

A, B1, B2, C, D1, D2

Times/Timouts in ms according to ISO/WD 15765.

UseExtAddr

When set to 1 the USDT component uses extended addressing. In this case ExtAddr also has to be configured. When set to 0 normal addressing is used.

ExtAddr

When UseExtAddr is set to 1 this parameter defines the byte used by the USDT component as extended address. When UseExtAddr is set to 0 this parameter will be ignored.

MsgLen

This parameter defines the message length USDT shall use. This influences the lower information block of the USDT component. When using a CAN component as hardware driver this parameter has to be less than 9.

See Also

AIDA Overview, list of AIDA components