9
Modbus protocol (Modbus/TCP)
Connection management
Manual – MOVIPRO
®
with EtherNet/IP™ or Modbus/TCP Fieldbus Interface
108
Objects
MOVIPRO
®
Object ID Designation Type M/O Category Value (example)
0x00 VendorName
ASCII
string
Mandatory Basic
SEW‑EURODRIVE
0x01 ProductCode SEW MOVIPRO
0x02 MajorMinorRevisons 823 568 0.10
0x03 VendorUrl
Optional Regular
www.sew.de
0x04 ProductName SEW MOVIPRO
0x05 ModelName –
9.3 Connection management
8 Modbus connections are possible simultaneously. Only one of the connections can
have write access to the process data range (controlling connection).
Connections that are no longer used must be disconnected by the fieldbus master. If
the slave detects an inactive connection, it assumes that the associated fieldbus mas-
ter is no longer active. In this case, the slave disconnects the connection that is no
longer in use. It is only then that the ninth connection can be established. If there are 8
active connections, the attempt to establish a ninth connection is canceled (socket is
closed on the server).
Connections 1–8 have the following characteristics:
• They operate independently.
• There is no prioritization.
• Only one controlling connection is permitted. This connection can change process
data.
If a controlling connection has already been established via EtherNet/IP™, you cannot
establish another controlling connection via Modbus/TCP.
The slave can at least buffer one frame with maximum Modbus length on receipt or
transmission.
9.3.1 Sending process output data (request controlling connection)
Process data can be sent only in the following cases:
• The connection is already a controlling connection.
• No controlling connection has been established yet.
When the device accepts the connection, it takes over the process output data into the
process sequence. As long as this connection is active, no other fieldbus master can
change the process output data (PO data).
16998413/EN – 12/2016
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