Hitachi SJ-P1 Series - Communication Specifications; Modbus TCP Frame Structure

7-2
Chapter 7
About the Modbus TCP
7.2 About the Modbus TCP
7.2.1 Communication specification
The protocol of this device is Modbus TCP.
■Communication specification
*1) Refer to the configuration of the parameter
[oH-02] (Communication speed (PORT1)) or
[oH-03] (Communication speed (PORT2)).
7.2.2 Modbus TCP frame
The frame structure of the Modbus TCP is shown
below.
*2) Do not connect this device to more than one of
the PC software (ProDriveNext: our product)
the same time. There is a possibility that data
conflict occurs and the operation will not be
performed properly when being access from
multiple ProDriveNext at the same time.
Items
Description
Communication method
(transmission speed)
Fixed transmission speed:
10Mbps Full/Half-duplex or 100Mbps Full/Half-duplex *1)
Auto detection transmission speed: Auto negotiation *1)
Auto MDI-X
According to selection of communication method (transmission speed), it is
to be configured as follows.
Selecting the auto negotiation: the function Auto MDI-X is available.
Selecting others: the function Auto MDI-X is unavailable.
Communication protocol
TCP/IP
Communication protocol
(application layer)
Modbus TCP
Maximum number of
sessions
4 *2)
Port number
502 (it can be configured by the inverter parameter setting),
[oH-05] (Modbus TCP port No. (IPv4)) or
[oH-06] (Modbus TCP port No. (IPv6))
Communication distance
Distance between nodes: 100[m]max
Modbus TCP ADU (*1)
MBAP Header (*2)
Modbus function code
Data
PDU (*3)
(*1) Modbus TCP ADU (Application Data Unit)
(*2) MBAP Header (Modbus Application Protocol Header)
(*3) PDU (Protocol Data Unit)