SMAR MB-700, Руководство пользователя

Страница: 57 / 116

Chapter 5
5.1
ADDING MODBUS TO THE MB-700
MB-700 as Serial MODBUS Master
Scenario
Figure 5.1 – MB-700 Architecture Example as a Serial MODBUS Master
Description
In this scenario the MB-700 has the following roles simultaneously, when the Bypass Direction
parameter is set for “TCP to Serial”.
¾
Bypass (TCP/IP to serial): The MB-700 passes the MODBUS message transmitting it to a lower
level of the network. The MB-700 acts as TCP/IP Modbus to serial Modbus RTU (485 ou 232)
converter.
¾
Concentrator: Modbus variables of the devices are read processed (Data Type conversion and
scale) and stored in parameters of the CCSM block. So instead of the HMI communicating
directly with the slave devices it will communicate directly with the MB-700 only.
¾
Peer-to-peer: Two Modbus slaves change data between each other. Peer-to-peer function
allows it. Slaves might be in different Modbus networks and even they can change data
between each other.
The system above is indicated for remote control operations, where the process is located in a not
easily accessible area, a place too far from the supervision system. User does not need to go to the
area, it is only necessary that he is connected to the Ethernet network.
The MB-700 has two serial ports EIA-232 and EIA-485 allowing connection with logic controllers
through a MODBUS network or through a MODEM. Using the EIA-485 port it is possible to create a
multi drop network with logic controllers or to integrate an already existent network. For remote
control, in distant locations, a modem or radio might be used in the EIA-232 port to establish
communication between the system HMI and configuration systems with controllers in the process
plant.