Bronkhorst Modbus slave interface - Manual (Page 13)

BRONKHORST ®
3 CHANGING SLAVE ADDRESS AND BAUD RATE
Default instruments will be delivered to customers on address 1 and with a baud rate of 19200 baud.
The slave address and baud rate of the Bronkhorst meter/controller Modbus slave can be changed to fit the
instrument in your existing Modbus network. Standard baud rates for Modbus are 9600, 19200 (default) and 38400.
3.1 Via rotary switches on the side of the instrument (if present)
On the side of the instrument are rotary switches placed and a label with the
explanation of the switches. Make sure to use a screwdriver which is suited for
the switches.
The switches have the following function: ADDRESS (00 – 99)
With the ADDRESS switch, the instruments address can be set. The MSD is the high part of the decimal number and
the LSD the low part. For instance address 25 means MSD on 2 and LSD on 5. The default switch position is 00. In this
position the address is software programmable. The default software programmable address is 1.
During instrument initialisation, the address switches are read. If the switches specify a valid Modbus address, i.e. a
value from 1 to 99, this value is used. If the specified address differs from the value stored in the instrument, the new
address is saved in memory.
Adjusting the rotary switches during operation will not affect the actual address unless the instrument
is re-powered and/or re-initialized.
When addressing by rotary switches is used, it's not possible to change the adress by RS-232 or by the
microswitch.
3.2 Via RS232: FlowFix
‘Off-line’ via the RS232 communication port by means of a special tooling program, called FlowFix.
FlowFix is a tool for multi-bus instruments that can be used for all field busses enabling the user to:
• Change slave address
• Read and optionally change the baud rate
• Make a service log file to be send to Bronkhorst in case of trouble
Connect your Bronkhorst meter / controller Modbus slave instrument to a free COM-port using the special cable with
on one side a T-part (with male and female sub-D 9 connector) and on the other side a female sub-D 9 connector (part
number 7.03.366). The single sub-D 9 connector should be connected to your COM-port and the female sub-D 9 of the
T-part to the male sub-D 9 of the instrument. Standard cables are approx. 3 meters. Maximum length between PC and
instrument allowed is approximately 10 meters.
Start-up FlowFix.exe and select the COM-port.
The configuration screen will appear.
Enter the Slave address and Baud rate and press [OK].
Valid values for the slave address are between 1 and
247, valid values for the baud rate are 9600, 19200,
38400, 57600 and 115200. The changed values will be
effective immediately after changing.
Page 13 Modbus interface 9.17.035