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It’s
possible to use DirectSOFT32 and the DSData Server to connect to an ECOM over the Internet.
While we don’t recommend that you use this
connection scheme for control, it can be quite useful for data collection, ladder
program updates, etc. If your Internet connection is through a gateway or proxy
server, it can still work, you just need to configure the gateway to
let the packets get through to the ECOM - this is discussed in Note 3 at the
bottom.
To demonstrate how this works, we
have setup an H2-ECOM here at Host Engineering you can use to test out the process. It’s in
a base with a DL250 CPU and some I/O. It’s IP address is 12.69.41.166. Follow
these instructions to build a link and get online with the ECOM.
First we need to determine the
approximate round trip time for an IP packet from your PC to the ECOM. We can
use Ping to get this number as follows:
Connect
to your ISP like you normally would – dialup connection, LAN connection, etc..
Open a Command
Prompt (DOS session). Enter the following on the command line:
Ping 12.69.41.166. Observe the average turnaround time.
Close the Command Prompt
window.
Next, you need to build a link to the ECOM.
Open
the DirectSOFT32 Launch Window
Create
a new link
right click "Comm Links" and
choose "Add Link..."
Click
the ‘Link Editor’ button
You have to manually build a link because
the default timeouts used in the Link Wizard may be too short when
connecting across the Internet, and since
the Link Wizard uses a broadcast to find the ECOMs on the network,
these broadcast packets will be filtered
out by the gateway and/or routers used to connect you to the Internet.
On
the PLC tab select the following:
PLC Family
Direct LOGIC 205 Series
PLC Type
250
On
the Port tab select the following:
Devices Ethernet
Transport
Winsock
Transport Protocol
UDP/IP
Node
Address
IP Address
12.69.41.166 *** see note 3 below about connecting through
a gateway or proxy server
Advanced Settings
Timeout
(Observed turnaround time +10%)
On
the Protocol tab select the following:
Protocols
ECOM
Click
Auto and the Link Editor should beep at you indicating a successful connection.
Enter
a name for your link and click Accept.
Go
online with the PLC!
right click the new
link and select Run
If you want to use this
scheme for your own ECOMs, there
two keys points you must observe to make this happen:
-
the ECOM must have a static IP address that is
unique on the Internet - that is, an IP address that has been assigned to you by
an ISP.
-
the ECOM must reside outside
any firewall or proxy
server, these devices typically perform 'IP translation' that will prevent the
ECOMs static IP address from being visible over the internet
-
if you must go through a
gateway or proxy server to connect to the ECOM, then you'll need to get the
administrator of the gateway or proxy server to create a "hole"
through the gateway to the ECOM. This "hole" is a mapping from an
IP on one side of the gateway to an IP address on the other side, sometimes
using a specific port number.
In our example, our internal network is using the 192.168.xxx.xxx addressing
range and the ECOM is using 12.69.41.166. So we create a UDP/IP mapping,
using the above addresses, specifying port 7070 (hex). So
whenever our gateway gets a packet bound for port 7070, it routes it to the
ECOM at 12.69.41.166.
We cannot give you specific steps to accomplish this because every
gateway/proxy server solution will have
different configuration steps. You just need to tell your IT person to
configure it for you, they should know how
to do this for their specific hardware/software.
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