Advantech Adam - 4021, User Manual, Page: 80 / 286

ADAM-4000 Series User Manual 68
4.1 Introduction
In order to avoid communication conflicts among devices trying to send data simulta -
neously, all the traffics are coordinated by the host computer. This action is initiated
by the host computer using a command/response protocol.
When the modules are not transmitting, they are in listening mode. The host issues a
command to a module with a specified address and waits for the module’s response.
If there is no response, a timeout aborts the sequence and returns the control to the
host.
Changing ADAM’s configuration might require the module to perform auto calibration
before changes may take effect. This is the case when the range is modified espe -
cially. The module has to perform all stages of auto calibration which is also per -
formed during the start up. When the calibration process is underway, the module
does not respond to any other commands. The command set in the following pages
includes the exact delays that might occur as modules are reconfigured.
4.2 Syntax
[delimiter character][address][command][data][checksum] [carriage return]
Every command begins with a delimiter character. There are four valid characters: a
dollar sign $, a pound sign #, a percentage sign % and an at sign @.
The delimiter character is followed by a two-character address (hexadecimal) that
specifies the target module. The actual two-character command follows by the
address. Depending on the command, an optional data segment may follows by a
command string. Furthermore, an optional two-character checksum may be
appended to the total string. Every command is terminated by a carriage return (cr).
ALL COMMANDS SHOULD BE ISSUED IN UPPERCASE CHARACTERS!
Before the command set is given, we provide an I/O module commands search table
to help you find the commands that you wish to use. The command set is divided into
the following three categories:

Analog Input Module commands

Analog Output Module commands

Digital I/O, Relay Output and Counter/Frequency Module commands
Each Category starts with a command summary of a particular type of module. How -
ever, they are explained in more depth at Chapter 5, 6 & 7 with detailed datasheets of
each individual commands.
Although commands in different subsections sometimes share the same format, the
effect they have on a certain module can be completely different from others. For
example, the configuration command %AANNTTCCFF affects analog input modules
and analog output modules differently. The full command set for every module is
listed below.