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The Extended Service Daemon (ESD) Protocol:

Communication between IGUANA modules is implemented with specific protocols, which were designed for the IGUANA gateway. One of these protocols is the ``ESD protocol'', which is dedicated to the communication between an Internet front-end and the ESD92.

The protocol is textual-based and stream-oriented, similar to the ``Simple Mail Transfer Protocol'' (SMTP) and consists of single line commands and according response messages, which may be basic (single line) and extended (multiple lines). Such a command/response sequence is shown in Listing 27 with the request in the first line and the response in the second.

language=XML
\begin{lstlisting}[caption={Example command/response messages in the
ESD protoco...
...!21@01:02:03:04:05:06 114 BINHEX \lq\lq nvoLedFb'' \lq\lq LED1 Feedback''
\end{lstlisting}

The addressing of a datapoint corresponds to the hierarchical addressing schema denoted above and is formatted as depicted in figure 42. An example address can be seen in listing 27.

Figure 42: Address Format in the ESD Protocol
\begin{figure}\centering
\includegraphics[scale=0.7]{graphics/iguana-address.eps}\end{figure}

The following commands are available in the ESD protocol:

READ:
This command retrieves the value of a datapoint in a requested encoding style. An example is given in Listing 28.

language=XML
\begin{lstlisting}[caption={Example READ request in the ESD protocol}
,label=ex...
...NHEX
0 LON.GATE1!21@01:02:03:04:05:06 BINHEX \lq\lq 01 0F A0 3F 6A''
\end{lstlisting}

WRITE:
The WRITE command writes a value to a datapoint in a specified encoding style. An example is given in Listing 29.

language=XML
\begin{lstlisting}[caption={Example WRITE command in the ESD protocol}
,label=ex_esd_write]
WRITE LON.GATE1!21@01:02:03:04:05:06 BINHEX
0 OK
\end{lstlisting}

DPINFO:
This command retrieves the properties of a datapoint. An example can be seen in Listing 27.
NODEINFO/ENODEINFO:
The Nodeinfo and Extended Nodeinfo commands can be used to retrieve the properties of a given fieldbus node.
Retrieving/Updating the Nodelist:
These commands can be used to retrieve a list of nodes that are connected to a fieldbus. Moreover, they can be used to update the list if nodes are disconnected or new nodes are connected to the fieldbus.
Commands regarding the event processor:
These commands can be used to create, delete or list events stored in the ESD.
Commands related to logging:
The logging commands are used to retrieve or clear logs associated to certain events.

Detailed information about the ESD protocol can be found in [LOB02].


next up previous contents
Next: Encapsulating the IGUANA Protocol Up: The IGUANA Gateway Previous: IGUANA Gateway Services:   Contents
Hermann Himmelbauer 2006-09-27