YOKOGAWA F3SP71-4S, User Manual

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2-1
IM 34M06P15-03E 2nd Edition: Jan. 31, 2012-00
2. Modbus/TCP Slave Function
This chapter describes the Modbus/TCP slave function via Ethernet.
2.1 Specifications
This section describes the functional and communication specifications of the
Modbus/TCP slave function.
„
Functional Specifications
The following table shows the functional specifications of the Modbus/TCP slave
function.
Table 2.1.1 Supported Modbus Slave Functions
Function Description Support
Serial communication Modbus communication via Serial
communication
No
Ethernet communication Modbus communication via Ethernet Yes
Write-protect function Function that prohibits device writing
using Modbus commands.
Yes
„ Communication Functions
The following table shows the communication specifications of the Modbus/TCP slave
function.
Table 2.1.2 Specifications of Higher-level Link Service Provided by Modbus/TCP Slave
Function (Ethernet)
Specification Item Specification
Communications
protocol
TCP/IP
Maximum number of
connections 8
(Total amount of TCP/IP connections of higher-level link
services)
Port number 502 ($01F6)
Command data format Binary
2.2 Communication Protocol
In Modbus/TCP frame, the module returns one response to each request received from
a higher-level computer (monitor or PC).
F020201.VSD
MBAP
Header
Data
Sending
station
Receiving
station
Modbus/TCP Application Protocol
Function Code
MBAP Header : Modbus Application Header
MBAP
Header
Data
Function Code
Figure 2.2.1 Communication Protocol