Introduction

An M580 network can accept the addition of DIO traffic through a BMENOS0300 network option switch module. The BMENOS0300 module can accept DIO data from these sources:

  • DIO daisy chain

  • DIO daisy chain loop

NOTE: Refer to the overview of typical RIO/DIO network topologies.

Each junction presents the queueing point, which can add delay or jitter to the system. If two packets simultaneously arrive at a junction, only one can be immediately transmitted. The other waits for a period referred to as one delay time until it can be transmitted.

Because RIO packets are granted priority by the M580 network, the longest an RIO packet can wait at a junction is one delay time before it is transmitted by the device or BMENOS0300 module.

The following scenarios depict how different junction types handle DIO packets that arrive simultaneously with RIO packets.

Network Option Switch Module

A BMENOS0300 network option switch module receives a steady flow of packets from both the main ring and the distributed equipment that is connected to the BMENOS0300 module.

The BMENOS0300 module handles RIO packets in this sequence:

Time

Main Ring In

DIO Sub-ring

Main Ring Out

Comment

T0

1

a (started)

–

Packet “1” arrived after transmission of packet “a” begins.

T1

2

b

a

Packets “2” and “b” arrive simultaneously.

T2

3

c

1

Packets “3” and “c” arrive simultaneously.

T3

4

d

2

Packets “4” and “d” arrive simultaneously.

T4

5

e

3

Packets “5” and “e” arrive simultaneously.