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ID TECH EzWriter
AMC Compatible Command Set
This command set provides EzWriter compatibility for existing software applications and
product replacements. Workshop can operate with the AMC command set; however, this
command set has some limitations not found in the IDT command set. Using Workshop
with the IDT command set is recommended.
USI Protocols
The AMC USI protocol is used for information exchange. The user may select from 2
different variations for communicating with the unit.
USI0 (Protocol 0)
In USI0, all characters are transmitted and received using exactly the command
characters listed in the chapter on Commands and Responses found later in this manual.
There are no Headers, Trailers, or Block Check Characters. Protocol 0 presumes no
transmission errors. This is the default protocol after a reader reset, although the reader
may be configured to respond in USI0 or USI1 for the power-on message. This protocol
also enforces a five (5) second maximum timeout between characters.
USI1 (Protocol 1)
In USI1, all messages are preceded by the ASCII character STX, followed by the ASCII
character ETX with one Block Check Character (BCC). The BCC is an XOR of the data
bits of the entire message including the STX and ETX characters. (It does not include the
BCC itself.) The parity of the BCC is the selected parity, if any. This protocol also
enforces a 65ms maximum timeout between characters.
If the Interface detects an error in an incoming transmission, it responds with a
"Retransmit". If the host detects transmission error, it may, at its option request a
retransmission.
Protocol Selection
After a power-on or reset, the unit is initialized to use USI0. After the unit receives a valid
USI1 message from the host, it continues to operate in USI1 until it experiences a power
reset or receives a WARM RESET command.
Note: The UIC – AMC compatible reader/writer has EEPROM settings for Protocol 0
or Protocol 1 that breaks the AMC Protocol auto shift rule. EzWriter follows AMC
protocol auto shift rule as described above.
Flow Control
For both protocols, the host may at any time stop/start the unit transmission by using the
XOFF/XON commands. After a power-on or reset, the unit is initialized to XON
(communications enabled) mode.
EzWriter, in the AMC mode, must get commands from the host to operate the LEDs.
Workshop sends these commands to EzWriter to emulate the IDT protocol operation.
