Bronkhorst Modbus slave interface - Manual (Page 7)

BRONKHORST ®
1 8
2 FIELD BUS INSTALLATION
2.1 General
Modbus is a 3-wire, RS485-based field bus communication system for parameter value exchange. In this system each
instrument / device is equipped with a micro-controller for its own dedicated task but also for exchanging parameter
value information with other instruments / devices connected to the same Modbus system.
The implementation of the Modbus interface is based on the following standards:
[1] Modbus_Application_Protocol_V1_1b.pdf December 28, 2006
[2] Modbus_over_serial_line_V1_02.pdf December 20, 2006
Physical layer and communication protocol are detected automatically upon reception of messages.
These messages must be sent using the correct combination of physical layer and communication
protocol. After every power-up the communication detection mode is active.
Bronkhorst advices not to use more as 127 instruments in one bus system.
2.2 Modbus connector
2.2.1 Shielded RJ45 modular jack
Warning: this device uses a vendor specific pin layout on the RJ45 connector that differs from the
Modbus recommended pin layout.
The shielded RJ45 modular jack connector (for non IP65 applications) has the following pin configuration:
RJ45 Connector Receptable Pin number Description
1
+15…24Vdc supply
2 0V
3 Shield
4 0V
5
+15…24Vdc supply
6 0V (Modbus common)
7 D0 Modbus (A/A')
8 D1 Modbus (B/ B')
The maximum contact rating for RJ45 connectors is 1.5A.
For MASS-VIEW instrument see manual 9.17.051 for pin layout.
http://www.bronkhorst.com/en/downloads/instruction_manuals/
Page 7 Modbus interface 9.17.035