Vishay G4, Technical Manual, Page: 106 / 200

Technical Manual
6-2
If the reply from a slave unit fails it may be due to:
•
Mismatch in communication parameters. (baud rate, address, . . )
•
More than one slave unit has been transmitting at the same time.
This can distort the reply message and make it impossible to decode.
See chapter ‘Communication
−
Modbus protocol’ section for detailed information of
register numbering, register content definition, commands etc.
More information about Modbus RTU can be found at ‘www.modbus-ida.com’ and
many other places.
Setup of Modbus RTU communication
•
The instrument will as default be given the address 1. If more than one
instrument is
used in a network, each G4 instrument must be given a unique address in
parameter ‘Modbus address’ (in ‘Parameter set-up’, menu ‘Communication’,
sub menu ‘Serial Com.’).
•
Set parameter ‘COMx:Mode’ to ‘Modbus Slave’.
•
Select correct baud rate and data format in parameter ‘COMx:Baudrate’ and
‘COMx:Data Format’.
•
Select wanted type of float values in parameter ‘COMx:Float Form.’.
•
When longer response times are needed, set ‘COMx:Min Reply T’ to a suitable
value.
Modbus TCP Slave
General
The Ethernet communication port can be used to communicate with the instrument
using the Modbus TCP protocol. The instrument is a Modbus TCP slave and will only
respond to incoming messages from a master.
See chapter ‘Communication
−
Modbus protocol’ section for detailed information of
register numbering, register content definition, commands etc.
More information about Modbus TCP can be found at ‘www.modbus-ida.com’ and
many other places.
Setup of Modbus TCP Slave communication
•
Network configuration (IP-address, netmask,….) must be done from menu
‘Network Configuration’.
•
Enable the Modbus TCP Slave by setting parameter ‘Modbus TCP Slave’ to
‘On’ in menu ‘Param. Set-up / Communication / Ethernet / Modbus TCP Slave’.
•
Select wanted type of float values in parameter ‘Float Format’ (also in menu
‘Modbus TCP Slave’).