Advantech Data Acquisition Modules ADAM 4000, User Manual

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Chapter
2
Chapter 2 installation Guideline 2- 9
2.3 Baud rate and Checksum
ADAM modules contain EEPROMs to store configuration
information and calibration constants. The EEPROM replaces the
conventional array of switches and pots that are originally used for
specifying baud rate, input and output range… etc.
Since there is no visual indication of a module’s configuration status,
it is impossible to know the baud rate, address and other settings just by
looking at it. It might not be possible to establish communications with
a module whose baud rate and address are unknown. To overcome this
problem, most modules have an input terminal labeled INIT*. Booting
the module while connecting the INIT* terminal with the module’s
GND terminal forces the configuration into a known state called the
INIT* state. Besides, some newer modules have INIT switch which you
can set “Init” or “Normal” (See Figure 2.4). If you set the switch to
“Init”, then it becomes INIT* state.
INIT* state defaults:
Baud rate: 9600
Address: 00h
Checksum: disabled
Forcing the module in INIT* state does not change any parameters
in the module’s EEPROM. When the module is in the INIT* state with
its INIT* and GND terminals shorted, all configuration settings can be
changed, and the module will respond to all other commands normally.
Changing Baud rate and Checksum
Baud rate and checksum settings have several things in common:
• They should be the same for all modules and host computer.
• Their settings can only be changed by putting a module in the INIT*
state.
• Changed settings can only take effect after a module is rebooted
To alter baud rate or checksum settings, you must perform the
following steps: