ProSoft Technology 5201-DFNT-DH485 - Manual (Page 11)

Functional Overview DH485 ♦ ProLinx Gateway
Driver Manual DH485 Interface
ProSoft Technology, Inc.
Page 11 of 44
August 27, 2009
2 Functional Overview
In This Chapter
™ Master/Slave Serial Port........................................................................ 11
™ Module Internal Database .....................................................................11
™ Protocol Functional Specifications......................................................... 15
The DH-485 protocol driver is designed to accept DH-485 commands from an
attached DH-485 master unit (that is, SLC 5/03 processor ladder logic message
instruction). The DH-485 driver permits a remote master to interact with all data
contained in a module. The data can be derived from other DH-485 devices on
the network through a master port on a module. The driver actively issues DH-
485 commands to other nodes on the DH-485 network. One hundred user-
defined commands are supported by the driver on each port.
2.1 Master/Slave Serial Port
Master mode issues read or write commands to other remote devices on the DH-
485 network. These commands are user-configured in the module via the master
command list received from the configuration file. Command status is returned to
the processor for each individual command in the command list status data area.
The location of this status block in a module’s internal database is user-defined.
The slave driver mode allows a module to respond to CIF and data read and
write commands issued by a remote node on the DH-485 network.
The Slave driver supports the following DH-485 command set:
Type Access Description
CIF Read 485CIF, Peer-to-Peer, Read MSG requests
CIF Write 485CIF, Peer-to-Peer, Write MSG requests
Data Table Read 500CPU, Peer-to-Peer, Read MSG requests
Data Table Write 500CPU, Peer-to-Peer, Write MSG requests
2.2 Module Internal Database
Central to the functionality of the module is the internal database. This database
is shared between all the ports on the module and is used as a conduit to pass
information from one device on one network to one or more devices on another
network. This permits data from devices on one communication port to be viewed
and controlled by devices on another port. In addition to data from the slave and
master ports, status and error information generated by the module can also be
mapped into the internal database.