Like its predecessor PROFIBUS, PROFINET is a diagnostic-rich protocol allowing your support team to quickly identify the source of device-related problems. This however is of limited use if the underlying performance of your network is poor. PROFINET networks are often seen as the plug and play solution for industrial networks, giving you the impression that successful completion of your application-specific testing is a guarantee that your network is working efficiently and without errors. This is fundamentally wrong and needs to be considered at the design stage as well as the acceptance stage of a project. This presentation will discuss the issues, how to address them and give typical examples of the equipment required.

1. PROFINET
Network Qualification
October 2015
Peter Thomas
(Control Specialists Ltd)
Chairman of the
PROFINET & PROFIBUS
International Training Centres
(PITC‘s)

2. PROFINET - Overview
2
PROFINET is a member of a family providing industrial
communications over Ethernet.
PROFINET is:
completely standard Ethernet (IEEE802.3).
High speed, operating at 100Mbit/s or faster over copper or
fibre-optic cables,
makes use of existing IT standards. But, is “real-time” and
deterministic,
PROFINET is very well thought out to incorporate all the
requirements of automation and control systems.
PROFINET is totally compatible with PROFIBUS but is NOT
PROFIBUS over Ethernet.

3. PROFINET – Flexible, Open and backward compatible
3
PROFINET

4. PROFIBUS v PROFINET
4
Feature PROFIBUS DP PROFINET
Network size 126 devices max. Effectively unlimited
Data Rate Up to 12M bit/s 100 Mbit/s
Update rate and
prioritisation
All devices have same
update rate and
priority
Different update rates
and priorities
Controlling Station Class 1 Master IO Controller
IO Equipment Slave IO Device
Diagnostic /
Configuration Tool
Class 2 Master IO Supervisor
Protocols DPV1, DPV2, DPV3
PROFINET RT, ARP,
DCP, SNMP, LLDP,
TCP/IP, HTTP, MRP
IT services Not possible Integrated in devices
Real-Time Yes Yes

5. PROFIBUS v PROFINET
5
Feature PROFIBUS DP PROFINET
Topology
Typically linear bus but
tree and ring possible
Linear, star, tree and
ring
Redundancy
Possible but
manufacturer specific
Simple and
standardised
Engineering access
Changes possible but
needs network restart
Possible without
disrupting operation
Standard Diagnostics Yes Yes
Alarms Only on DPV1 Yes, with priority
Addressing By switch or over bus Over network
Network Devices
Repeaters, Hubs,
OLM’s
Switches
Termination Switch-selectable Built into connector
Cable
2 core shielded
twisted pair
4 core shielded
twisted pair

6. PROFINET – Real-time v TCP/P
6

7. PROFINET – In operation
7
PROFINET
HTTP SNMP Socket
IP
TCP / UDP
Sensor system
PROFINET
PLC
PC
SNMP/OPC server
PROFINET
Field devices
PC
Internet Explorer
Real-Time
RT IRT
Ethernet
PROFINET allows for different data rates for different applications
within the same network.

8. PROFINET - Topology
8
PROFINET wiring is quite different to PROFIBUS
PROFIBUS:
Uses multi-drop segments with many devices on one cable. Segments are separated
by repeaters.
Two-core screened twisted pair cable.
Termination is in the hands of the user – many problems arise because of this.
PROFINET :
Multi-drop connection is not used; all cables connect just two devices together.
Switches are used for branching to devices.
Four-core screened twisted pair cable.
Termination is provided within every Ethernet device; no longer in the hands of the
user – should eliminate termination problems.

9. PROFINET – Physical Layer
9
Ethernet defines the physical layer and data link layer.
Modern Ethernet is defined by the IEEE802.3 standard.
PROFINET uses 100Mbit/s switched full duplex communication over
copper or fibre optic cable.
100 BASE-TX copper
cabling
100BASE-FX fibre optic cabling

10. PROFINET – Physical Layer (Cable)
10
4-core shielded twisted pair cable.
Link Class D - Cat5 or Cat5e cable for use at up to 100MBit/s.
Characteristic impedance 100Ω.
Cable length up to 100m maximum
TD+ yellow
TD- orange
RD+ white
RD- blue

11. PROFINET – Physical Layer (Connectors)
11
PROFINET connectors are available for:
• “Inside use”
– Within control rooms or cabinets
– RJ45 pattern
– Generally at least IP20 rated.
• “Outside use”
– Exposed to the environment (field mounted)
– RJ45 pattern or
– M12
– Generally IP 65 to 67 rated

12. PROFINET – IO Devices
12
Ethernet
IO-Controller
Configuration
Control/monitoring
Alarms
DiagnosisDiagnosis
Status/Control
ParametersIO-Device
PROFINET Supervisor
E.g. PLC running application
program.
E.g. PC or laptop running
engineering tool application.
E.g. Field device with
inputs/outputs
(Compare with PROFIBUS
Class-1 master)
(Compare with PROFIBUS
Class-2 master)
(Compare with PROFIBUS Slave
device)

13. PROFINET – Commissioning Guideline
13
• This is one of several free-to-download guidelines documents
from PNO (PROFIBUS and PROFINET User Organisation).
• It provides guidance on how to verify the installation aspects
of the network as well as how to commission the live system.
• These tests are additional to the application-specific, System
Acceptance Testing that would usually be performed.
Failure to follow these guidelines puts you at risk of having your
application tests pass without a detailed knowledge of the
underlying performance of your network !

14. PROFINET – Installation Acceptance
14
These are associated with the cabling of the installation and include:
• Visual Checking of the cabling.
• Point-to-Point electrical testing of the cabling using a simple line
tester.
• Point-to-point acceptance testing of the cabling using an Ethernet
Function tester.
Installation Acceptance tests should ideally be performed by individuals
who have Certified PROFINET Installer accreditation.
This is a one day course accredited by PI and delivered by organisations
that have PI-certified Training Centre accreditation.
There are two such organisations in the UK.

15. PROFINET – Installation Acceptance – Visual Checks
15
• The guideline lists 23 individual checks that should be
performed on each cable. Examples are
• Cable laid according to plan?
• Maximum length of 100m observed?
• Cable screen earthed at both ends to a previously proven
earthing system.
• Cable separation rules followed?

16. PROFINET – Installation Acceptance – Line Checks
16
The main criteria for the simple electrical
testing of PROFINET cables are:
• There are no short-circuits between any
wires.
• There are no short-circuits between any
wire and the screen
• There are no wire breaks.
• The shield is connected at both ends.
• The wire pairing has been observed
correctly.

17. PROFINET – Installation Acceptance – Function Testing
17
• Simple line testers are designed to test the
electrical aspects of the cable.
• The more advanced function and acceptance
testers establish the ability of that cable to
successfully transmit predefined data packages
as well as determine cable length, attenuation
and cross-talk.
• Such tests are very useful as a baseline in the
event of needing to perform such tests at a
later date.

18. PROFINET – Commissioning
18
These are associated with the operational aspects of the installation and
should only be performed on completion of the Installation Acceptance
tests.
• Checking that the addressing and naming of all IO devices are in
conformance with the design specification.
• Determining other device-related information such as MAC addresses,
Firmware versions etc.
• Establishing that the topology is in conformance with the design
specification.
• Establishing the absence of discarded and error telegrams.
• Establishing operational characteristics – IO Device Cycle time, Net
load, Jitter, Broadcast.
Installation Acceptance tests should ideally be performed by individuals
who have Certified PROFINET Engineer accreditation.
This is a three day course accredited by PI and delivered by
organisations that have PI-certified Training Centre accreditation.

19. PROFINET – IO Device Identification
19
• Every PROFINET device has a world-wide unique MAC address
assigned by the manufacturer.
• The MAC address is unique to that particular device and will
change if the device is replaced with a spare.
• Before a device can take part in communications with an IO
Controller, it must have been configured with a PROFINET Device
Name. This is usually done with the configuration software of the
IO Controller (e.g. Siemens TIA Portal) but can also be done using
readily available PROFINET tools.
• When the IO Controller initialises communication with the IO
Device, it will allocate an IP address to it.
• Every IO device will also have manufacturer-specific hardware
and/or firmware versions.
• Note - All real-time communications takes place using MAC
addresses.
MAC Address: 00: 0E:CF:04:68:7A
Device Name: MySensorName123
IP Address: 192.168.1.23
HW Version: 1.0
FW Version: 1.24

20. PROFINET – Topology
20
Line
Tree
Star
Ring
PROFINET is very flexible when it
comes to laying out the network.
However, each of the four shown
come with advantages and
disadvantages that need to be
considered at the design phase.
It is important o ensure that the
actual topology is in conformance
with that described in the design
specification.

21. PROFINET – Topology – Line Depth
21
• Line depth is the number of forwarding switches between an IO Controller and an IO Device.
• The line depth will affect the cycle time that the device can be polled at.
• The choice of switch (store & forward / cut-through) also affects this (see next slide).

22. PROFINET – Topology – Switching technology
22
STORE & FORWARD
CUT-THROUGH

23. PROFINET – Test for “Discarded Packets”
23
• A switch may discard packets due to transmission problems or internal queue overflows at high
network loads.
• This should be evaluated over a period of 60s at high network loads.
• During this period, there should be no discarded packets.
Missing Packets at high Load

24. PROFINET – Test for “Net load”
24
• This is defined as the % of bandwidth used by the real-time communications.
• It should be checked at every IO Controller.
• The ideal value is <20%.
• Values in the range 20% to 50% - further investigation required.
• Values > 50% require actions to reduce the net load
Testing for Net Load

25. PROFINET – Test for “Broadcasts and Multicasts”
25
• Occasionally, broadcast and multicast telegrams will appear on the network.
• These are telegrams that all devices on the network will respond to. Typical examples
include:
• ARP broadcasts – Address Resolution Protocol telegrams are used during entire
scans of the network and initiated by engineering systems, diagnostic tools and IT
systems. Values > 0 and for entire IP ranges should be investigated.
• DCP multicasts – Device & Configuration Protocol telegrams are generated by an IO
Controller on start-up to search for devices with a given device name prior to
allocating an IP address. Values > 10 are considered high should be investigated,
those > 20 are considered too high for trouble-free operation.
• MRP multicasts – Media Redundancy Protocol telegrams are used to determine data
flow direction in ring topologies. Values > 0 should be investigated.
Note – these values can be checked at any point on the network, including a spare port on a
switch.

26. PROFINET – Test for “Jitter”
26
The organisation of PROFINET timing ensures that real-time communication with
a particular device is achieved with a regular update time.
However, it is possible that delays within switches and devices can cause the
transmission time to vary from cycle to cycle.
Such variable delays can give rise to “jitter”.
Jitter is something that should be evaluated.
Update time
Time
Jitter Jitter

27. PROFINET – EMC Criteria
27
• EMC (Electromagnetic Compatibility) and Protective
Earth (PE) issues are acknowledged as being the cause
of a significant number of problems on Fieldbuses and
Industrial networks like PROFIBUS and PROFINET.
• This is because of the ever-increasing frequencies that
such systems operate at.
• Simply ensuring that the cable screen is connected to
earth at both ends serves no purpose if the earth loop
impedance at “typical” frequencies is too high.
• The screen impedance of all PROFINET cables should <
0.6 and the current >0mA AND < 40mA.
• The impedance of the Functional Earth at “typical”
frequencies should be <0.3 .
• Any values outside of this range should be
investigated.

28. PROFINET – Monitoring Tools - Operational Qualification
28
TO PROFINET NETWORK
Internet Explorer
This permanent monitoring solution can
be used during qualification and on-
going support.
It has no effect on the PROFINET
network which will continue to operate
even if power to the monitor is
removed.
24v
Volt-Free Contact to PLC

29. PROFINET – Acceptance Specification
29
• This document acts as a formal record of the
installation and operational qualification tests.
• It should clearly define roles and responsibilities.
• Define the type of tools required to perform the tests
and typical specifications.
• Each test should cross-reference back to the
appropriate section in the relevant design specification.
• Have clear descriptions of the tests and unambiguous
acceptance criteria.
• There should be space available for the tester to
sign/date each test and make notes.

30. Peter Thomas
(Control Specialists Ltd)
Chairman of the
PROFINET & PROFIBUS
International Training Centres
(PITC‘s)
Peter Thomas
Control Specialists Ltd
PROFINET – Questions?