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.
<som>
Start-of-message (ASCII # character)
<seq>
Sequence number (ASCII hex digit) that represents an odd number in the range 0–9,
A–F (1, 3, 5, 7, 9, B, D, F). The host should use odd sequence numbers in its command
since the MPRX uses even sequence numbers in its transmissions. This method
eliminates the possibility of a synchronous host command and an asynchronous reader
transmission having the same sequence number.
Upon receiving a host command in ECP, the MPRX replies using the command’s
sequence number in its response. Therefore, the host device updates its sequence
number upon receipt of a valid reader response. If the sequence number is not
updated before transmission of the next command, the MPRX will not service the new
command; it will retransmit its previous message. A command/message sequence is
not complete until the host updates its sequence number.
MPRX User Guide
TransCore Proprietary
4–46
Содержание MPRX 10-7200-001
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