MSR120 Programmer’s Manual UDN PM010, Rev. 1.1
Section 3 -- Technical Specification 2003/1/21
Host Command Reader Response
Comment
02h 50h 03h 51h
Ready to read
02h 5Eh 03h 5Fh
Reader ACK
Protocol 2
In Protocol 2, all messages are preceded by the ASCII character <SOH>, followed by a one byte reader address,
one byte character count and terminated with a one byte <BCC>. The <BCC> is an XOR of the characters (8 bits)
in the entire message, including <SOH>.
Format: <SOH><ADDRESS><00Hex><COUNT><MESSAGE><BCC>
or
<SOH><ADDRESS><00Hex><00Hex><MESSAGE><EOT><BCC>
where STX=02Hex and ETX=03Hex.
Table 3-5. Example for Protocol 2
Host Command
Reader Response
Comment
01h 00h 00h 01h 50h 50h
Ready to read
01h 00h 00h 01h 5Eh 5Eh
Reader ACK
The <ADDRESS> field is for a multi-reader system. This function is not currently supported. The recommended
value for this field is NULL (00Hex), however, any value will work.
If the value of <COUNT> fields are zero, an <EOT>, followed by the <BCC>, completes the message. The reader
may, at its option, use NULL for COUNT when transmitting.
For Protocols 1 and 2, if the reader detects an error in an incoming transmission, it will respond with a
“Communications Error” message. If the host detects a transmission error, it may request a retransmission. Both
protocols enforce a 100mSec timeout between characters.
For all Protocols, the host may, at any time, stop/start the reader transmission by using software “handshake”
(DC3/DC1) or hardware “handshake” (if enabled in EEPROM configuration) by controlling the CTS line.
Transmission Format
Data output format (Self-ARM mode)
Protocol code Tk1 prefix
Tk1 Data Tk1 suffix
EOT
BCC
Protocol code Separator Tk2 prefix Tk2 Data
Tk2 suffix EOT BCC
Protocol code Separator Tk3 prefix TK3 Data Tk3 suffix EOT BCC
Read data for command
Read tk1 data for command
Protocol code Tk1 prefix
Tk1 Data Tk1 suffix EOT BCC
Read tk2 data for command
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