2.1 Use 3G or 4G mobile internet connection when wired internet connetion is not available .............................................................................. 2
2.2 Designed to handle mobile internet ..................................................................................................................................................................................... 2
3.0 System overview................................................................................................................................................................................................................................... 2
3.1 3G / 4G data connection set-up for SCADA systems ........................................................................................................................................................ 2
3.2 3G and 4G connections ................................................................................................................................................................................................................ 3
3.3 IP addressing .................................................................................................................................................................................................................................... 3
3.4 DynDNS service .............................................................................................................................................................................................................................. 3
4.3 DynDNS service provider ............................................................................................................................................................................................................ 4
4.4 SCADA server with OPC server software ............................................................................................................................................................................... 4
Operating guide ECL Comfort 296 / 310 via 3G / 4G to SCADA server
2.0 Introduction
2.1 Use 3G or 4G mobile internet connection when wired internet connetion is not available
The ECL Comfort 296 / 310 controller can be connected to a SCADA
system via a 3G or 4G mobile internet connection if a wired internet
connection is not available. Some important limitations and
restrictions apply however, if a 3G or 4G mobile internet connection
is used.
2.2 Designed to handle mobile internet
When a connection is less reliable then the SCADA server and the
ECL Comfort 296 / 310 controller may experience the connection to
be lost.
This situation sets higher demands for mechanisms to re-establish
the connection and also higher demands for retransmission and error
handling mechanisms.
3.0 System overview
3.1 3G / 4G data connection set-up for SCADA systems
The components are shown in the drawing below.
Mobile internet connec tions are in general to be considered as being
less reliable and having lower data throughput than wired internet
connections.
The Danfoss ECL Comfort 296 / 310 controller and OPC Server are
designed to handle mobile internet connections being less reliable
than wired internet connections.
The OPC Server software must, however, be configured accordingly.
Operating guide ECL Comfort 296 / 310 via 3G / 4G to SCADA server
3.2 3G and 4G connections
The data throughput is typically lower in a 3G or 4G mobile internet
connection than in a wired internet connection. 4G is though faster
than 3G. Data throughput depends on both the bandwidth and also
on the latency time.
Bandwidth on fast 3G or 4G connections may be comparable to bandwidth of wired internet connections in ideal situation, but it may be
affected by signal quality, signal strength and often depends also
on other users utilization of the total bandwidth available from the
mobile internet connection provider’s antenna.
3.3 IP addressing
IP addressing is also often different from wired internet connections as mobile internet connections typically use a dynamic
private IP address which is renewed/changed regularly and static
IP addressing is seldom an option.
It must be ensured that the IP address of the 3G modem is public
instead of private, i.e. accessible by other devices/servers on the
internet.
3.4 DynDNS service
To avoid the need for a static IP address of the 3G or 4G modem
the DynDNS service can be used.
Latency time is though significantly longer in mobile internet connections which results in significantly reduced performance of the
Modbus protocol.
The OPC Server must be configured to tolerate this longer response time to requests. The performance of the SCADA system
also benefits from limiting the amount of data and sensor values
etc. requested from the controllers.
The IP addressing topic is important to SCADA systems as the
communication scheme typically used is that the SCADA server
initiates Modbus-TCP connections to the ECL Comfort 296 / 310
controllers and therefore needs to know the IP addresses of the
controllers.
The SCADA server will then be able to access the modem by addressing the URL of the modem.
This service translates a URL, which is user defined, but unique to
each modem, into the current IP address of the modem.
The modem must send its IP address to the DynDNS service provider whenever its IP address changes.
3.5 Costs
Costs typically apply to mobile internet connections which are
based on the amount of data transferred to and from the modem.
In the calculation of the data transmitted to and from the modem
not only the known data generated by the SCADA server is included, but also any other irrelevant and unwanted data transmitted
by other devices on the internet to the IP address of the modem.
The modem must support the DynDNS service and an account at
the DynDNS service provider must be available.
Flat rate subscriptions may be an alternative to achieve a fixed cost
independent of transmitted and received data.
Another alternative is a private network or virtual private network
(VPN) which ensures that only the controllers and SCADA server
within such network can exchange data.
Operating guide ECL Comfort 296 / 310 via 3G / 4G to SCADA server
4.0 Components overview
Please see ‘System overview’ on page 2 where the placing of the components is shown in a drawing.
4.1 ECL Comfort 296 / 310 controller
• Connected to 3G modem via Ethernet cable
• Configured for STATIC IP
4.2 3G modem
• 3G modem with Ethernet interface
• Built in router. The router must be configured to forward
incoming traffic from WAN to LAN on TCP Port 502 to the IP
address of the ECL Comfort 296 / 310 controller.
Preferably, it should forward only the traffic received from the IP
address of the SCADA server.
• Built in firewall. The firewall must be configured not to block in-
coming traffic from WAN to LAN on TCP Port 502.
• Built in support for DynDNS (preferred). DynDNS must be
configured to use the user’s DynDNS account. If DynDNS is not
used/supported then the IP address on the WAN side of the 3G
modem must be public and static (special subscription at
mobile internet service provider is typically needed).
Security note:
The Modbus/TCP implementation guide does not specify a
specific security model.
The ECL Comfort 296 / 310 controller does not use any form for
access control restriction and it is therefore strongly advised to
only use it on a secure network where a router/firewall provides
security to other local networks or the internet. In most routers
it is possible to set simple access restrictions for which kind of
internet traffic that are allowed to reach the ECL Comfort 296
/ 310 controller.
4.3 DynDNS service provider
• User account at DynDNS service provider must be created.
• The URL specified by DynDNS for the 3G modem, i.e. xyxyxy.
dyndns.info, must be known.
4.4 SCADA server with OPC server software
• Must have OPC Server for ECL Comfort 296 / 310 controller
installed.
The devices (ECL Comfort 296 / 310 controller communicating
via 3G)
created in the OPC Server must be configured to use Modbus TCP connection to the URL specified by DynDNS and TCP Port
502.
• Polling rates and timeouts must be specified carefully to
achieve reliable communication via 3G. Max. polling rate may
have to be increased from default value. Read and write time outs typically have to be increased from default values, i.e. to
5000ms. The suspend period, e.g. the period a device is sus pended from communicating if some timeouts (timeouts to
suspend) have occurred, may also have to be increased from
defaut value.
See example on the other side of page.
Modbus/TCP communication is not affected by the removal
of the key from the ECL controller. It is still possible to change
all settings through communication even if the key has been
removed in order to prevent this!
Screenshot of the OPC Server software for ECL Comfort 296 / 310 controller.
The example indicates important settings to make when using a 3G /
4G connection.
AQ085786472248en-010301
Operating guide ECL Comfort 296 / 310 via 3G / 4G to SCADA server
Disposal note
This symbol on the product indicates that it may not be disposed of as household waste.
It must be handed over to the applicable take-back scheme for the recycling of electrical and electronic equipment.
• Dispose of the product through channels provided for this purpose.
• Comply with all local and currently applicable laws and regulations.