User's Manual

Serial communication protocol
Note: To configure the A740 RTU, you must have a special adapter cable (available from
Adcon) and plug it into the POWER connector.
1. Open a HyperTerminal window.
2. Select the appropriate serial port and click OK.
3. Configure your terminal as follows:
• 19200 baud
• 1 stop bit
• 8 data bits
• No parity
• No protocol (neither hardware nor software)
4. Select OK to open the terminal window.
5. Press Enter to generate a response in the window.
3.5 Serial communication protocol
This protocol is based on a master sending commands and a node answering; the
whole communication is conducted in plain ASCII, as strings. When exchanging
numbers, they are represented in decimal format. All commands are terminated
with a CR/LF combination. All responses (answers) are terminated with the #
character.
3.5.1 General format of a command
The commands have the following format:
[ID] Command Param1 Param2 ... ParamN
• ID (optional) is the destination device. If you include an ID as part of a
command, the node checks whether ID=ownID. If it does, the node
executes the command on itself. If the ID is not the node’s ID, the node
executes the command on a remote device, if such an ID exists. If the ID is
missing, this implies that the command is addressed locally.
Note: Not all the commands can be relayed remotely.
• Command is the command proper, which can be composed of a variable
string of characters (for example,
INFO). Each node can implement a set of
commands depending on the functionality of the node itself. However, as a
minimum requirement, a node recognizes the CMDS command, which
returns a list with the commands recognized by the node.
• Param1 Param2 ... ParamN represent the parameters, which are
command dependent. If you type no parameters when you issue a
command, it is the equivalent of querying for information (the GET version
of a command). If you type parameters, you are issuing the SET version of
a command and are setting the command to the parameters you typed.
3.5.2 General format of an answer
The answers have the following format:
27