Dh485 serial port driver access to database, 1 dh485 serial port driver access to database – ProSoft Technology 5201-DFNT-DH485 User Manual
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DH485 ♦ ProLinx Gateway
Functional Overview
DH485 Interface
Driver Manual
Page 12 of 44
ProSoft Technology, Inc.
August 27, 2009
2.2.1 DH485 Serial Port Driver Access to Database
The module supports the common interface file (CIF) of the DH-485 protocol. A
separate data area can be defined for each application port. This data area is
divided into read and write data and is mapped into the module’s internal
database. The module’s application constantly transfers the read CIF data from
the CIF database to the module database and the write CIF data from the
module to the CIF database. The parameters used to define the CIF database
are contained in the configuration file. This optional feature of the module should
only be utilized if required by a remote master on the network. Otherwise, the
data file functions (500CPU message) instructions should be used to access and
control the module’s data. The following diagram shows the relationship of the
DH-485 drivers, the CIF database and the module’s database:
Module
Database
Write
Function
Read
Function
Master Driver
Write
Function
Read
Function
Slave Driver
CIF
Database
Request
Response
Request
Response
Request
Response
Request
Response
Read Database
Read Database
Write Database
Write Database
Write CIF Request
Read CIF Request
CIF Write Data
CIF Read Data
The Master driver uses the database in two ways:
1 A read command issued to a slave device by the master driver will return the
slave data into the internal database
2 A write command issued to a slave device by the master driver uses the data
in the internal database to write to the slave device. The slave driver
accesses data from the internal database. External DH-485 master devices
can monitor and control data in this database through the slave port. Setup of
the slave port only requires the CFG file.