This presentation by Westermo’s Technical Lead Engineers Dakota Diehl and Benjamin Campbell, is an integral part of the Westermo webinar on March 26th 2020, covering how to get older network technology to communicate over new protocols and equipment, and bridging the gap in technologies without replacing legacy equipment. Watch it here: https://www.westermo.com/news-and-events/webinars/accessing-the-edge-with-legacy-communications

1. Robust Industrial Data Communications – Made Easy
Accessing the Edge
With Legacy Communications

2. 2
Overview
 Team Introduction
 Introduction to Westermo
 Ethernet Medium
 SHDSL
 Serial Modems to IP Migration

3. 3
Introductions
Dakota Diehl
Network Application Engineer
dakota.diehl@westermo.us
847.453.3899
Benjamin Campbell
Technical Support Engineer
benjamin.campbell@westermo.us
847.453.3896

4. 4
Westermo group 2020
 Founded in 1975
 Industry leading software and
hardware development force
 Own production in Sweden with
state of the art process control
 Own sales and support units in 12
key countries, distribution partners
in many others

5. Robust Industrial Data Communications – Made Easy
Serial Data vs Ethernet Data

6. 6
Serial Data Differences
 Serial Data (In this case, referring to RS-232/422/485 standards) is defined as data
that transfers one bit-at-a-time. As information is received from the software, it is
sent to a remote port where it is received in chronological sequence.
 Serial ports control timing and sequence of data sent over the serial interface, in
order to confirm that the data is usable.
 Because each byte of data must be sent in sequence, data speed and distances are
limited. Endpoint devices also expect data in a certain order as otherwise data can
become corrupted.
 In Ethernet, all data is packetized, and sent as a packet over a network. Packets may
take many routes to a destination and can be received in different chronological
orders for the endpoint device to arrange correctly.
How do I get my Serial data over Ethernet?

7. 7
10011000011110001000100010010100101111
Serial to IP (Packetisation)
• Data from the sending device is buffered before sending
Serial data
Serial data is buffered
before sending

8. 8
Serial to IP (Packetisation)
• The buffered data is placed in an IP packet and sent over the network
IP Packet + serial datagram

9. 9
10011000011110001000100010010100101111
Serial to IP (Packetisation)
• The IP wrapper is stripped off and the serial datagram is replayed out the serial port

10. Robust Industrial Data Communications – Made Easy
Mitigating Potential Issues

11. 11
Serial over IP Takes Longer
10011000011110001000100010010100101111
Serial data
10011000011110001000100010010100101111
Serial data
IP Packet + serial datagram
T1 T2 T3
Time serial data is on the wire
e.g. T1
100 bytes @9600 8,n,1 = 104ms
Total transmission time over IP broadband
including processing time will vary
depending on media in
e.g. T2 = 40ms
Replay serial data on the wire
e.g. T3
100 bytes @9600 8,n,1 = 104ms
T1 + T2 + T3 = 248ms
Between 2-6 slower than a Legacy modem connection

12. 12
Mitigating Time Delays
10011000011110001000100010010100101111
Serial data
10011000011110001000100010010100101111
Serial data
IP Packet + serial datagram
T1 T2 T3
Time serial data is on the wire
e.g. T1
100 bytes @57600 8,n,1 = 17.4ms
Total transmission time over IP broadband
including processing time will vary
depending on media in
e.g. T2 = 40ms
Replay serial data on the wire
e.g. T3
100 bytes @57600 8,n,1 = 17.4ms
Speeding up the serial baud rate reduces the time on the wire
and reduces the overall delay
Total time of transmission = 74ms

13. 13
Mitigating Time Delays
10011000011110001000
Serial data
100010010100101111
Serial data
T1 T2 T3
Datagram = 100 bytes
Send a new IP frame after every
5 bytes
First datagram send after 5.2ms
Total transmission time over IP broadband
including processing time will vary
depending on media in
e.g. T2 = 40ms
Replay serial data starts on recite
of first IP frame 5.2ms
Largest time delay caused by buffering the whole serial message
Breaking the message into small pieces as it received and sending
over the IP connection speeds up transmission
Data now look’s like it is stream
5 bytes5 bytes5 bytes5 bytes5 bytes

14. 14
10011000011110001000100010010100101111
Mitigation using Virtual Serial Ports
Ip connection
directly to SCADA server
Virtual serial ports
Comm 11
Comm 12
Comm 13
|
Comm 20
Comm 21
Serial data
No replay time at the receiving side IP frame is forwarded directly to the
application via the virtual serial ports

15. 15
IP Packet + serial datagram
Mitigation using Virtual Serial Ports
IP connection
directly to SCADA server
Virtual serial ports
Comm 11
Comm 12
Comm 13
|
Comm 20
Comm 21
No replay time at the receiving side IP frame is forwarded directly to the
application via the virtual serial ports

16. Robust Industrial Data Communications – Made Easy
Ethernet Mediums

17. 17
Traditional Ethernet
Traditional Cat5e or Cat6 cable!
 RJ-45 Connector
 Handle 10/100/1000 Mb/s speeds
 Widely used as an industry standard
 100m or 328’ distance limit
 Longer distances require an alternative!

18. 18
Cable alternatives
Fibre
Distance up to 120 km (75 miles)
+ Lightning protected
+ Low attenuation
+ High bandwidth
- Expensive contacting
- Demanding installations
- Dust sensitive
Twisted pair
Distance up to 15 km (9 miles)
+ Existing cables can be used
+ Low cost
+ Simple installation
- Low bandwidth
- Sensitive towards surge and lightning

19. 19
SHDSL (Single-Pair High-speed Digital Subscriber Line)
 Full duplex on a single twisted pair
 DSL technology
 International standard–G.991.2
 Symmetric (uplink/downlink)
 Line speed up to 30.6 Mbit/s (with bonding)
 Distance up to 15 km (9 miles)
 Point to point
 Transparent
 Plug and play CPE initiates the connection
with the CO
 Speed is negotiated based on line
characteristics
 Quality of the line is measured through SNR
(Signal to Noise Ratio) dB
CO
(Central office)
Responder
CPE
(Customer Premises
Equipment)
Initiator

20. 20
SHDSL – Things to Consider
 Strive to always use twisted pair cables to
avoid crosstalk.
 Twisted pair also reduce interference from
other signals since the pair is balanced.
 Cable area > 0.3 mm2 (AWG 22)
 If external surge and lightning protectors
will be used, ensure they have the right
characteristics.
In some legacy situations, cables were
designed to carry simple switched DC so
there was no need for twisted pairs.
Would it be possible to use this type of cable?
 These lines are prone to pick up more electrical noise
than twisted pair cable, due to the cables used being
unbalanced.
 This cable may work but it needs to be tested, while
data rate and maximum distance will be reduced.

21. 21
Assuring Quality SHDSL Connections
 Measure the line quality through the SNR
value.
 Test different pairs and choose the best
ones.
 If possible, perform long time test.
 If possible, do not use a pair close to other
used pairs.
 After test, use the same pair at installation
 If shielded cable is used connect earth only
to one end of the cable.
 Grounding the cable on both ends can cause
ground loops, along with additional noise on
the line.

22. 22
How to measure SNR?
DDW-142 and DDW-242 have LED detection
on the front measuring SNR in steps of 3 dB.
 SNR< 3 dB this cable is not reliable, try
another pair.
 SNR 3 to 5 dB this cable will work but we
recommend you to try to improve the
SNR value.
 SNR 6 to 9 dB this connection will work
connectivity can be guaranteed.
 SNR> 9 dB high quality connection.

23. Robust Industrial Data Communications – Made Easy
Serial Modems to IP Migration

24. 24
Why Migrate from Serial Modems to IP?
 Regulation and technology shifts are forcing change in the telecoms market
 Leased Lines are being phased out
 Dialup modems are struggling to communicate over new telecoms system
 CSD over 2G is being phased out globally
 ISDN is rapidly disappearing
 More data in near real time is becoming the norm (Big Data)
But!
 Millions of the remote devices still use serial RS-232 and modems to communicate to
the SCADA, DCS or remote maintenance.
 How can the gap in technologies be bridged without replacing the legacy equipment?

25. 25
Legacy Leased line
Telecom
Leased Line
Serial
RS-232
Serial
RS-232

26. 26
Legacy modem communications (Streaming)
• Analogue, ISDN and CSD 2G cellular modems all stream serial data
10011000011110001000100010010100101111
Approx. 40-120ms
delay dependig on
modem and
modulation
Datagram
Datagram is received at the serial port
and modulated onto the carrier signal in
a continuous stream

27. 27
Legacy modem communications (Streaming)
100110000
Approx. 40-120ms
delay dependig on
modem and
modulation
Datagram
The datagram is streamed out
of the serial port after the
demodulation process
10111111110001000100010010100

28. Robust Industrial Data Communications – Made Easy
Leased line over IP Broadband

29. 29
Internet
Leased line replacement
Broadband network
xDSL
xDSL
SerialSerial
VPN
VPN (Virtual Private Network) becomes the leased line replacement
VPN provides a point to point link over the Internet
Encryption ensures the data remains private

30. 30
Internet
Mobile
Network
3/4G
VPN
Leased line replacement
Broadband network
VPN
(Virtual Private network)
Serial
Serial
VPN’s are media independent

31. 31
Typical utility digitisation project
Scaling up options;
• Use existing serial ports
• Install virtual serial port software
• Install virtual modem software
• Direct addressing from SCADA or DCS system

32. 32
Serial and IP devices sharing connectivity
Ip connection
directly to SCADA server
10011000011110001000100010010100101111
Serial data
IP Packet + serial datagram
IP and serial devices can share the broadband/VPN connection.
IP only communications

33. 33
Increasing availability
10011000011110001000100010010100101111
Serial data
VPN
VPN
IP

34. 34
Conclusion
 Serial communications can be sent over Ethernet with some changes to packetization
 Changing to IP broadband does not mean the remote devices have to change
 There are many option to replace and improve on the legacy modems
 The media over which IP broadband travels has many options as well
 SHDSL, Fiber, Cellular, VPN through the Internet, etc.
 Moving to IP broadband can increases availability
 OPEX costs can drop when moving to IP broadband connectivity

35. 35
Next Month’s Webinar:

36. 36
Robust Industrial Data
Communications – Made Easy