![background image](http://html.mh-extra.com/html/wire-wizard/gas-tracker/gas-tracker_installation-and-operation-manual_988434018.webp)
16
GAS TRACKER INSTALLATION & OPERATION MANUAL
APPENDIX A
Modbus Integration
Overview
The
Gas Tracker
supports integration with a PLC or personal computer through Modbus RTU over
RS-485 or USB. RS-485 is preferred for integrating with PLCs or other embedded devices. Using
the USB interface may be more convenient when integrating with a personal computer. This
interface allows the user to query unit status like gas flow rates, remaining gas in cylinder and to
retrieve alert statuses.
When connected to a personal computer through USB, thew device will appear as a COM port.
Modbus requests can be sent over this virtual serial port. Serial port settings such as baud
rate and parity have no influence on the virtual serial port and can be set to anything. The USB
interface always identifies as Modbus device ID 0x01.
The RS-485 interface provides more configuration options. The user can specify the baud rate
and parity options by clicking
Setup
in the left menu and then pressing
Modbus
on the
Setup
page. The baud rate can be set to either 4800 or 9600. The parity can be
None, Even
or
Odd
. As
per the Modbus specification, two stop bits are used with None parity, and one stop bit is used
with Even and Odd parities. If the bus is shared, match the baud rate and parity to that of other
devices on the bus, otherwise a baud of 9600 and a parity of None are the best defaults.
Modbus has been an industry standard since 1979, and with minor changes in the early years,
has remained largely unchanged. Because of its longevity, it has a large presence in factory
automation and control.
Connector
The Modbus connector is Euro-style (also referred to as a Euro Block)
3.5mm pitch screw terminal connector. Replacements can be purchased
from a handful of suppliers.
▶ Phoenix Contact, BCP Series #5441210
▶ Adam Tech, EB Series #EBKA-03-A
MODBUS
D+
D–
GN
D
Summary of Contents for GAS TRACKER
Page 2: ......