Page 12 Draft Rev. AX5
AdvanTag 9100 Technical Manual
Chapter 2: Theory of Operation
AdvanTag Gateway
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USING HSMS PROTOCOL AS HOST. The HSMS protocol can be used in two modes
ACTIVE mode and PASSIVE mode. The ATR gateway would be used as a PASSIVE
device. In this mode of operation, the ATR Gateway opens up a socket which would listen
for an incoming connection request from an ACTIVE HSMS host. After the initial
handshake, a connection between the Host and the ATR gateway is established. Once a
connection had been established, the host and ATR Gateway can exchange messages
between each other.
To establish a connection with an ATR Gateway, the following gateway specific
information must be present with the host:
• ATR Gateway IP Address: The IP address of the ATR Gateway must be known to
the host so that a connection request could be made on that address. Please note
that HSMS is an IP address associated protocol thus for HSMS communication IP
address of the Passive entity must be known to the Active entity.
• ATR Gateway Port Number: The ATR gateway opens a listening socket as
mentioned earlier but the connection is opened on an ETHERNET PORT. This
number also must be used by the Active entity (the host) to establish a
connection.
NOTE . . .
IT MIGHT BE NOTED THAT THE IP ADDRESS ASSIGNED TO THE ATR GATEWAY
WOULD BE A STATIC IP ADDRESS AND NOT ONE OBTAINED VIA DHCP SERVER.
THE REASON FOR THIS IS THAT HSMS IS AN IP ADDRESS BASED PROTOCOL.
Message Format and Translation
The messages as described in Section 1.1 have to be of the CIDRW SECS and ASCII
standard. The host could communicate with the ATR Gateway on either the RS-232 port
or the ethernet port. On the RS-232 port, the host could communicate over SECS or
ASCII version. When the host communicates over the ethernet, the communication would
happen over the HSMS protocol.
Each CIDRW SECS message (either on the SECS or HSMS port) would have a target ID
in its message body as an item. For example, the command Read MID (S18F9) has the
format
S18F9 : 'S18F9' W
<A '##'>. * Target ID.
The item ## represents the Target ID of the node which the host wants to access.
Assuming the host needs to read the MID from node '09', following is the sequence of
operations that would take place.
1. Host sends S18F9 command to the ATR Gateway.
2. ATR Gateway parses the message for validity of data and format and extracts the
Target ID out of the data stream.
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