TransCore 0596465PT15 Manuel D’Utilisation

The host computer initiates synchronous communications between the Encompass 4H 
Reader and the host. The host begins a sequence by issuing a command; the Encom-
pass 4H Reader 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 Encompass 4H 
Reader 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 
Encompass 4H Reader 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 Encompass 4H 
Reader replies using the command’s sequence number in its 
response. Therefore, the host computer updates its sequence 
number upon receipt of a valid reader message. If the sequence 
number is not updated before transmission of the next command, 
the Encompass 4H Reader 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.

<cmd>

Command code, a string that contains from two to four ASCII 
hex characters

[<data>]

Optional data field, an ASCII string of as many as 20 characters 
in length. For example, the store hardware configuration string 
command is #696S...S or command #696 Store Hardware 
Configuration String followed by the data string S...S.