User's Manual

PIN Pad 791 Programmer’s Manual (PCI POS-A) UDN PM0103-U Rev. 06
Section 9 – Online transaction messages with Master / Session keys 2015-04-20
Page224
Uniform Industrial Corp. Proprietary and Confidential Total 342 pages
Message flow:
HOST Direction PP791
Message Z2 or Z3


<ACK> (Good LRC)
<NAK> (Bad LRC)
<EOT> (after 3 NAKs)
Show prompt message
Message Z50


<ACK> (Good LRC)
<NAK> (Bad LRC)
<EOT> (after 3 NAKs)

Message Z51
(or <EOT> when input
cancelled)
<ACK>/<NAK>/<EOT>
