Intermec DCS 300, User Manual, Page: 228 / 452

DCS 300 User’s Manual
8-20
About the $IPT Transaction ID
$IPT is a special transaction ID that contains the protocol that allows JANUS RF
devices and Trakker Antares terminals to communicate with the DCS 300 using the
direct TCP/IP socket interface. Every transaction from a device needs $IPT as the
transaction ID, which allows the server DevComm to route the data to the proper queue.
When a device receives a transaction from the DCS 300, the transaction does not
contain $IPT, but the protocol is the same.
$IPT offers these features:
•
Client requests permission to open a socket. The client sends a data packet that
contains the OPEN command, session ID, port number, host name, and maximum
packet size to the DCS 300.
•
Client receives a packet from the DCS 300 that acknowledges the request.
– Client receives an
OPEN_NAK
(negative acknowledgment) packet from the
DCS 300, which indicates the request to open a socket has failed.
– Client receives an
OPEN_ACK
(acknowledgment) packet from the DCS 300,
which indicates the request to open a socket has succeeded.
•
Client sends and receives data to and from the host through the DCS 300. The data
packet contains the DATA command, the session ID, and the data.
•
Client requests permission to close the socket or it receives a
CLOSE
packet from
the DCS 300 indicating that the connection is closed.
About the Host Application Requirements
The DCS 300 to host interface does not require any modifications. Host applications
must be written using the standard TCP/IP socket interface. Also, host applications
must be server applications; that is, they open a socket and wait for a client connection
to arrive at the socket.