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Operation of the I/O Link
The I/O Link consists of a full duplex communications channel. Physically, the link consists of two twisted pairs of wire and a signal ground conductor. These wires are contained in a cable that has an over±all shield. Signals are of the differential type and a wire pair is used for each signal. Signal levels are compatible with specification EIA RS±422/RS±485. The signal baud rate is 1.5 Mbaud maximum.
Input and Output Data
The master on an I/O Link can send 1024 outputs and receive up to 1024 inputs from slave devices. A slave can send and receive either 32 or 64 inputs and outputs. For each link device, inputs and outputs have the same meaning:
HInput Data is data received from the link.
HOutput Data is data sent to the link.
So the same set of data is considered output data by the device that sends it and input data by the device that receives it.
a45008
MASTER
INPUTS
SLAVE
INPUTS
OUTPUTS
OUTPUTS
For each Series 90±70 I/O Link Interface Module used as a master, %I and %Q references and data lengths for each slave are assigned within the application Program Block, using Logicmaster 90. Instructions for doing this are given in chapter 4. For other types of devices on the link, references and data lengths are assigned differently. For details on how a specific type of device handles its I/O Link data, you should refer to the User's Manual for that device.
GFK±0644A | Chapter 1 Introduction | 9 |
