Io-Link Protocol - Siemens SIMATIC ET 200AL System Manual

System overview

2.4 IO-Link protocol

2.4 IO-Link protocol
Operating modes
The IO-Link port of the master can be operated in the following modes:
● IO-Link:
The port is located in the IO-Link communication.
● DI:
The port behaves like a digital input.
● DQ:
The port behaves like a digital output.
● Disabled:
The port is disabled.
Transmission rate
In the IO-Link specification V1.1, three data transmission rates (baud rates) are specified for
the IO-Link operating mode:
● COM 1 = 4.8 kBaud
● COM 2 = 38.4 kBaud
● COM 3 = 230.4 kBaud (optional according to Specification V1.0)
The IO-Link device only supports one of the defined data transmission rates. The IO-Link
master to Specification V1.1 supports all data transmission rates and adjusts automatically to
the data transmission rated supported by the device.
Response time of the IO-Link system
The response time of the IO-Link system provides information about the frequency and
speed of the data transmission between device and master. The response time depends on
various factors.
A value for the minimum cycle time of the device is stored in the device description file IODD
of the device (Page 17). This value indicates in which time intervals the master may address
the device. The value has a big influence on the response time. The master also has an
internal processing time that is factored into the calculation of the response time.
Devices with different minimum cycle time can be configured on a master. The response
time for these devices differs accordingly. In other words, the response time for various
devices connected to a master can vary greatly.
When you configure the master you can specify a fixed cycle time in addition to the device-
specific minimum cycle time stored in the IODD. The master then addresses the device
according to this specification.
The typical response time for a device thus results from the effective cycle time of the device
and the typical internal processing time of the master.
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Function Manual, 12/2017, A5E31637677-AB
IO-Link system