Introduction

What Is a Network Interface Module?

Purpose

An island of STB I/O modules requires a network interface module (NIM) in the

 

leftmost location of the basic island. Physically, the NIM is the first (leftmost) module

 

on the island bus. Functionally, it is the gateway to the island bus—all

 

communications to and from the island bus pass through the NIM. The NIM also has

 

an integrated power supply that provides logic power to the island modules.

The Fieldbus

 

An island bus is a node of distributed I/O on an open fieldbus network, and the NIM

Network

is the island’s interface to that network. The NIM supports data transfers over the

 

fieldbus network between the island and the fieldbus master.

 

The physical design of the NIM makes it compatible with both an Advantys STB

 

island and your specific fieldbus master. Whereas the fieldbus connector on each

 

NIM type may differ, the location on the module front panel is essentially the same.

 

Other NIM connectors, such as the power supply interface, are identical for all NIM

 

types.

Communications

 

 

Roles

The NIM manages the exchange of input and output data between the island and

 

the fieldbus master. Input data, stored in native island bus format, is converted to a

 

fieldbus-specific format that can be read by the fieldbus master. Output data written

 

to the NIM by the master is sent across the island bus to update the output modules

 

and is automatically reformatted.

Integrated Power

 

The NIM’s built-in 24-to-5 VDC power supply provides logic power to the I/O

Supply

modules on the basic segment of the island bus. The power supply requires a

 

24 VDC external power source. It converts the 24 VDC to 5 V of logic power,

 

providing 1.2 A of current to the island. Individual STB I/O modules in an island

 

segment generally draw a current load of between 50 and 90 mA. (Consult the

 

Advantys STB Hardware Components Reference Guide [890 USE 172] for a

 

particular module’s specifications.)

 

A basic NIM supports up to 12 Advantys STB I/O modules.

 

 

890USE19600 April 2004

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Schneider Electric INTERBUS Basic Network Interface Module, 890USE19600 Version 1.0 What Is a Network Interface Module?