Download Modbus Map - Meters USA

This chapter will mainly discuss how to handle the meter via the
communication port using software. To master this chapter, you should
be familiar with Modbus and have read other chapters of this manual,
and you have generously mastered the function and application of this
product.
This chapter includes: Modbus protocol, format of communication and
data address table and Acuvim II application details.
5.1 Introducing Modbus Protocol
The Modbus RTU protocol is used for communication in Acuvim II. The
data format and error check met hods are defined in Modbus protocol.
The half duplex query and respond mode is adopt ed in Modbus protocol.
There is only one master device in the communication net. The others
are slave devices, waiting for the query of the master.
Transmission mode
which is compatible with Modbus RTU Mode*.
Coding System
Start bit
8-bit binary
1
Data bits
Parity
Stop bit
8
no parity
1
Error checking
CRC check
Framing
Address
8-Bits
Function
8-Bits
Data
N×8-Bits
Table5.1 Data Frame Format
74
Check
16-Bits