NEO 2 Interface Developer’s Guide
Copyright © 2019, International Technologies & Systems Corporation. All rights reserved.
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Note
: In this mode, if a collision is detected, the reader will interpret further
‘Communication Error’ or ‘Card Not Present’ events as being caused by collision.
8.25.2.2.
Improved Collision Detection
Enabling this mode disables Standard Collision Detection mode and changes reader behavior:
1.
While polling, the reader will attempt to find the PICC using the standard polling
method.
2.
If a collision is detected, the reader will abort the transaction and notify the POS.
3.
It will report this with an error in the data field of its response (0x21, collision error).
Tag DF7F enables/disables Improved Collision Detection. When this tag is set to zero (default
value), Improved Collision mode is disabled. When this tag is set to another value (1-255),
Improved Collision mode is enabled.
When Improved Collision mode is enabled, the DF7F tag value defines the number of
successful sequential polling attempts required for signal lock. For example, if tag DF7F = 3,
then the reader must detect a card successfully three times in a row before the firmware
decides this is a successful polling attempt. Given the same conditions, the reader must fail to
detect a card three times in a row before the firmware decides this is a 'card not present'
polling attempt.
To reiterate, Improved Collision Detection requires a specified number of polling attempts to
complete without an EMV collision event before the RF signal is locked to a specific card. If an
EMV collision event is reported, the transaction will end and return a collision status code.
The following table summarizes the tag-related information provided above.
Feature
Tag
Length
Value
Notes
Improved Collision
Detection
DF7F
1 byte
0 = default
Improved Collision Detection Disabled (one
successful polling attempt is sufficient for
signal lock).
1 – 255
Improved Collision Detection Enabled. Number
of successful sequential polling attempts
required for signal lock.
In this new mode, the collision scenarios have been improved in the following manner:
1.
Increased sensitivity to improve collision detection generally. Previously, silent card and
garbled receive were not identified in the same manner as a standard collision.
2.
If the transaction times out due to any of the collision methods described previously, the
serial response will reflect this in its error state, with Status Code 0x08 (Time Out) and
Error Code 0x21 (Collision Error).