Chapter Five
Specifications
Man_805U Rev 1.8
Page
37
4.5
Hayes Commands
The 805U unit may be configured by a host device using Hayes AT commands.
Configuration may be done “off-line” by a user (with a PC terminal as the host device) or it
can be done automatically “on-line” by a host device such as PLC or SCADA. The AT
commands are ASCII messages designed for use with conventional telephone modems.
Before a 805U unit will accept Hayes commands, it must be in “command” mode. A host
device may force the unit to command mode by sending a sequence of three “escape”
characters - “+++”. The default escape character is “+”, however this may be changed as it
is one of the configuration parameters. There must be a 1 second break of data before and
after the escape sequence. The 805U can be configured to start up in command mode (or
alternately in operating mode). It would be normal for the modem to start up in command
mode when used in single-connect controlled mode.
Once in configuration mode, the 805U unit will accept a string of Hayes commands, and the
configuration changes made. The changes will not however be stored in permanent memory
(EEPROM) unless the Hayes command for recording the configuration (AT&W) is sent.
When the configuration changes are made, the module must be put back into its operating
mode by using the “online” Hayes command,
ATO
Commands are entered in the format ATxy, where x selects the parameter, and y the value of
the parameter. For example, ATB2 sets the radio data rate to 76800 baud. B selects the
radio rate parameter and 2 is the value corresponding to 76800 baud.
Summary
Enter command mode
<1sec break> + + + <1 sec break>
Response from 805U
OK
Enter configuration commands
ATxy
Response from 805U
OK
Save configuration
AT&W
Exit command mode
ATO
Note that some commands will automatically exit command mode. Several commands can
be run together, for example, ATB2&WO is the same as ATB2 and AT&W and ATO
Prior to Configuration
Before configuring a module initially, force the module to its factory default configuration -
either by using the DIP switches (refer section 4.3), or by using the AT&F command. If you
are making a change to an existing configuration, this step is not necessary.
Appendix A details all of the Hayes commands accepted by the 805U. The following
commands are the most common.
Configuration of addressing
AT&S
System Address Range 0-255 Default set by factory.
AT&G
Group Address Range 0-255. Default 1.
