This command enables to extend the waiting time for the response from the PCD. This command is required in case the host needs a longer time than FWT (see description of the Iso14CE.ActivateCardAPDU command) to prepare a response APDU to the last request APDU from the PCD. After calling this command, the PICC repeatedly sends WTX requests to the PCD for WaitingTimeout ms.

This command should be run in BRP Continuous Mode , since it can explicitly be stopped by the host by executing the Break command. If this command is not run in BRP Continuous Mode, the reader has to wait for the WaitingTimeout duration before finalizing the execution of the command.

The WTX request refresh interval may be accommodated with the WTXM and RefreshRatio parameters according to the formula:

t(refresh) = FWT * WTXM * RefreshRatio / 100.

By default, the waiting time is renewed every (0.9 * FWT) ms (WTXM = 1, RefreshRatio = 90).

Please note that according to the ISO/IEC 14443-4:2008 specification, the maximum allowed value for FWT and for the extension FWT * WTXM is 4949 ms.

This command should only be used if the AutoWTX parameter in the Iso14CE.ActivateCardAPDU command is set to 0. Otherwise, the card emulation automatically takes care of extending the frame waiting time.


Parameters (request frame)

Name Type/Size Description
WaitingTimeout Integer (16 bits) Time (in ms) for which the emulated PICC should send WTX requests repeatedly. A value of 0xFFFF corresponds to an infinite value.
WTXM Integer (8 bits) Waiting Time Extension Multiplier (WTXM). This parameter extends the actual frame waiting time (FWT) by this multiplier (FWT_temp = FWT * WTXM). WTXM has to be comprised between 1 and 59.
RefreshTimeRatio Integer (8 bits)

Together with parameter WTXM, this value defines the WTX request refresh cycle time interval:

t(refresh) = FWT * WTXM / RefreshTimeRatio.

The value range of RefreshTimeRatio is 0..100. t(refresh) is expressed in ms.

Returned values (response frame)