Rockwell Automation Publication 871FM-UM002A-EN-P - April 2017
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871FM Miniature Metal Flat Pack with IO-L
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Overview
Chapter 3
Transmission Rates
Three baud rates are specified for the IO-Link device:
• COM 1 = 4.8 kBd
• COM 2 = 38.4 kBd
• COM 3 = 230.4 kBd
An IO-Link device typically supports only one of the specified transmissions
rates, while the IO-Link V1.1 specifications requires an IO-Link master to
support all three baud rates. (See Product Specifications for product baud
rate.)
Transmission Quality
The IO-Link communication system operates at a 24V level. If a transmission
fails, the frame is repeated two more times. If the transmission fails on the
second try, the IO-Link master recognizes a communication failure and signals
it to the controller.
Response Time of the IO-Link System
The device description file (IODD) of the device contains a value for the
minimum cycle time of the device. This value indicates the time intervals at
which the master can address the device. The value has a large influence on the
response time. In addition, the master has an internal processing time that is
included in the calculation of the system response time.
Devices with different minimum cycle times can be configured on one master.
The response time differs for these devices. When configuring the master, you
can specify a fixed cycle time and the device-specific minimum cycle time that
is stored in the IODD. The master then addresses the device that is based on
this specification. The typical response time for a device therefore results from
the effective cycle time of the device and the typical internal processing time of