TransCore MPRX, System Manual

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System Guide
TransCore Proprietary 6–6
If the timeout delay expires before the MPRX receives an
ACK
or
NAK
message from the host, a logical
NAK
condition will be declared. If the
MPRX receives a
NAK
or timeout, the reader retransmits the data message.
When the MPRX receives an
ACK
message, the system software treats
the message as having been properly received by the host. The software
increments the sequence number, and advances pointers to the next
message in the MPRX’s message queue to prepare for sending the next
message.
Switch to Command Mode Request
The host device may issue command
#01
Switch to Command Mode while in data
mode.
The basic protocol format is as follows:
<som><cmd><eom>
The ECP format is as follows:
<som><seq><cmd><crc><eom>
where
<som>
Start-of-message (ASCII # character)
<seq>
Sequence number generated by the host device separately from that
appearing in data messages transmitted by the MPRX
<cmd>
Switch to command mode (ASCII characters 01)
<crc>
CRC value for the message
<eom>
End-of-message character (ASCII CR)
Host Transmission
The host device initiates synchronous communications between the MPRX and the host. The
host begins a sequence by issuing a command; the MPRX responds accordingly.
The data inquiry protocol format is as follows:
<CTRL-E>
The basic protocol format is as follows:
<som><cmd>[<data>]<eom>
The ECP format is as follows:
<som><seq><cmd>[<data>]<crc><eom>
where
<CTRL-E>
ASCII Control E (hex 5 digit). When in data inquiry mode, each transmission
of a CTRL-E by the host causes the MPRX to transmit one tag ID.