MSR120D Programmer’s Manual UDN PM009 Rev. E
Section 3 -- Technical Specification 2005/2/23
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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