Why is Tag 8A Giving a Z3 Response Code?

'Z3' is the correct response code when the terminal is unable to go online, but sometimes 'Z3' shows up in tag 8A when it's not expected. Why?

Basically, if you send a result code to the reader that is not recognized by the kernel, the kernel will change it to 'Z3' (5A33). For example: the kernel may not be recognizing result code 3035. Instead, it gets changed to 5A33 ('Z3').

Solution: You can use tag DFEE1B to define your three response codes: Approved/Referral/Decline.

DFEE1B is defined as 8 bytes long:

Bytes 0/1 are for Approved Code

Bytes 2/3 are for Referral Code

Bytes 4/5 are for Declined Code

Bytes 6/7 are Reserved for Future Use (RFU).

Example: If the host uses 3030 as APPROVED, 3031 as REFERRAL, and 3035 as DECLINED, you would make sure the following TLV is included in your terminal settings:

      DFEE1B 08 3030 3031 3035 0000

Once DFEE1B is properly defined with the DECLINE = 3035, then the kernel will recognize and properly process the transaction.

NOTE: To set the tag on a per-transaction basis, you can send DFEE1B in the emv_completeTransaction() method, in the Universal SDK, or provide DFEE1B in the "extra tags" of the Complete Transaction parameters in the Universal Demo app.