ESD electronic CAN-CBM-PLC/331-1, Hardware Manual

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Overview
esd Protocol for CAN Modules Rev. 3.2 1 - 2
1.4 General Hardware Functions
To use the esd CAN protocol at the CAN modules at each module the following hardware circuits are
necessary:
CAN controller SJA1000 (or compatible)
The controller has a internal RAM, that is used as a working memory. In this RAM the
dynamical parameters are stored. The RAM is deleted with each RESET.
I²C EEPROM
The I²C EEPROM is used for storing the configuration parameters. The data will remain stored
in power off condition or after a RESET.
Coding switch
Via the coding switch, e.g. the default value of the module no. is set. Valid module no’s are
from $00 up to $FE. The value $FF is reserved for the ‘Advanced Configuration’.
Further descriptions can be read in the hardware manual of the module.
1.5 Parameters after a RESET
The module offers various possibilities to trigger a RESET:
A power-on RESET and a RESET by the general command 'RESET module' reset the local
components.
Furthermore the module is able to trigger a RESET independently when the hardware watchdog has
expired. This RESET also resets the local components without changing the stored parameters.
The listed RESETs only change the parameters of the module filed in the I²C EEPROM, if the
conditions apply which are listed in the table below.
The module also supports the command 'default RESET'. By this command a local RESET is triggered
and the parameters of the module are always overwritten with the default parameters.
The used parameters with which the module operates after a power-on RESET or a RESET by the
general command 'RESET module', depend mainly on three factors:
The switch position of the coding switches, the availability of the I²C EEPROM data and the module
number (parameter 'module no.') stored in the I²C EEPROM.
The following table should give an overview of the resulting parameters. It does not contain the 'default
RESET', because this does always lead to the activation of the default parameters.