DURAG D-LX 200, Руководство пользователя

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Modbus
D − LX 200, D − LX 720
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8 Modbus
This chapter deals with the device-specific areas of the Modbus interface and
the Modbus implementation for the D
− LX 200, D − LX 720. This description
therefore does not provide complete information on all areas of the Modbus
protocol.
General information on Modbus and the DURAG Modbus can be found in the
separate DURAG Modbus Manual and on the Internet
(http://www.modbus.org/).
The (  ) RS-485/field bus interface of the D − LX 200, D − LX 720 is used to
provide parameters and settings, and to query the current status. The Modbus
protocol is used.
The data communication is Master(Client) / Slave(Server) . The Compact
Flame Monitor acts exclusively as "slave", i.e. it only reacts and responds to
valid Modbus queries at the request of the Modbus master.
The RS-485/Modbus interface enables data transfer over large distances (up
to 1200 m) and parallel connection of a number of devices (max. 32 are
provided for). The data cables must be implemented as twisted pairs.
8.1 Hardware and boundary conditions
The Compact Flame Monitor D − LX 200; D − LX 720 is equipped with an
RS485/Modbus interface.
The RS485/Modbus data connection is established using connection terminals
7 (RS485 A) and 8 (RS485 B) or, in the case of a preassembled connection
cable, using the pink (RS485 A) and the grey wires (RS485 B). In the case of
RS485/Modbus data communication, correct termination of the data bus or
RS485 interface must generally be ensured.
For this purpose the D − LX 200, D − LX 720 is equipped with a 120 ohm
terminating resistance on printed circuit board no. 4, which can be activated by
jumper X2 (see Figure 8.1 and Table 8.1 on page 84).
8.2 Setting the Modbus slave address
The D − LX 200, D − LX 720 is connected to the PC either with an RS232/RS485
or a USB/RS485 adapter (see connection plan Figure 11.1 page 103).
The interface configuration of the PC must be set
before starting the software,
i.e. the USB/RS485 adapter must be bonded and installed.