User's Manual

PIN Pad 791 Programmer’s Manual (PCI POS-A) UDN PM0103-U Rev. 06
Section 10 – Online transaction messages with DUKPT 2015-04-20
Page253
Uniform Industrial Corp. Proprietary and Confidential Total 342 pages
Message 7A KSN output format
Format: <STX>7A[KSN_format] <ETX>[LRC]
Message length: Fixed 6 bytes.
Usage: This message will set the key serial number (KSN) format of message 71 (DUKPT
frame). Format 0 is the original mode (strip leading ‘F’ of KSN) which is compatible of
PP690, PP790SE and PP791, Format 1 is full mode (output full 20 characters of KSN).
Message element:
Field Length Value and description
<STX> 1 <02>
7A 2 Message ID
[KSN_format] 1 ‘0’: message 71 output KSN without leading ‘F’
‘1’: message 71 output KSN with leading ‘F’.
<ETX> 1 <03>
[LRC] 1 Checksum
Message flow:
HOST Direction PIN pad
Message 7A


<ACK> (Good LRC)
<NAK> (Bad LRC)
<EOT> (after 3 NAKs)