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Data Exchange
116
890USE17700 April 2004
Data Exchange with the STB NIP 2212
Introduction Data exchange between a Modbus over TCP/IP host or the HTTP embedded web
server and the Advantys STB island bus is conducted over the Ethernet port on the
STB NIP 2212.
Master Devices The input and output data image areas (See The Island’s Process Image Blocks,
p. 168) can be accessed and monitored over the Ethernet LAN by a
Modbus over TCP/IP fieldbus master or the STB NIP 2212 HTTP embedded web
server.
The Ethernet port on the STB NIP 2212 is configured as follows:
Port 502 SAP—Modbus over TCP/IP
Port 80 SAP—HTTP
Port 161 SAP—SNMP
Modbus over
TCP/IP
Communications
Master devices use Modbus messaging (See List of Supported Commands, p. 135)
to read and write data to specific registers in the process image. The Modbus
protocol is understood regardless of the network type.
The Modbus protocol uses a 16-bit word data format.
Data Exchange
Process
Data stored in the process image is exchanged between the STB NIP 2212 and the
Ethernet network via Modbus over TCP/IP. First, data from the Ethernet host is
written to the output data image area (See The Output Data Process Image, p. 119)
in the NIM’s process image. Then, status, echo output, and input data information
from the I/O modules on the island are placed in the input data image area (See The
Input Data and I/O Status Process Image, p. 120). In this location, the Modbus
master can access them over the TCP/IP network, or over the CFG port.
Data within the output and the input areas of the process image is organized in the
order that the I/O modules are assembled (See A Data Exchange Example, p. 118)
on the island bus.
Note: An HMI panel or a device running the Advantys configuration software can
also exchange data with an island via the CFG port (See The CFG Interface, p. 33)
on the STB NIP 2212.