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MCT-CM
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11 Communications
This section provides instructions on how to use the MCT communication interfaces. As a standard, the MCT
is equipped with both an Ethernet interface and an RS232 serial interface for user communications.
11.1 Ethernet Communications
The MCT provides several options for remote control and monitoring over the Ethernet communications
interface. The web server interface provides a monitor only connection, while the VNC server and Modbus
TCP interfaces allow a user to manipulate and control the MCT remotely. The VNC interface allows the user
to view and observe operation of the MCT display directly on their PC screen while the Modbus TCP interface
allows the user to manipulate MCT operation via other devices and/or software capable of Modbus TCP
communications.
NOTE: In order to use Ethernet communications, the MCT must be properly connected to a network. To
connect the MCT to a network, connect the
touch screen’s Ethernet port to your network using a
standard CAT5 cable connection. Note that after connecting the network cable, it may be necessary
to cycle power to the MCT in order for it to obtain a valid IP address.
11.1.1 Guide to Smart Networking Practices
The expansion of Ethernet onto the industrial floor has brought forth a new realm of possibilities from the
gathering of information to the inherent control of equipment from anywhere around the world. The flexibility
and convenience that this provides makes it a very desirable feature for new equipment. The MCT provides
this ability, but there are considerations that must be taken by the end user to protect their equipment and
investment.
Just like placing a personal computer on the internet opens it up to outside attack, placing your MCT on a
network poses the same risk. The first thing to remember is this: The most likely cause of problems is not a
hacker trying to sabotage your equipment, but more often to be related to the ubiquity of PCs with Ethernet
cards, the ease with which your own co-workers can
“hang stuff on the network”, and careless or nonexistent
internal security measures. Accidental problems are more common than deliberate ones.
Allowing anyone access to the MCT by placing it on the office LAN, also opens the door for accidental shutdown,
damage to equipment, loss of data, lost time, etc. This is possible even by the most well-intentioned co-workers.
Thus, there are several steps that should be taken to minimize this risk.
The first is to never mix your office LAN with your control LAN. The control LAN should be a separate network
that consists of your MCT controller(s) and possibly any other equipment that you may have that is related to
the operation of the system. It should be separated from your office LAN by a firewall, or at minimum, a bridge
or router. A control network and a business network have two entirely different purposes and their interaction
should be closely controlled.
It is also unwise to assume that any Ethernet capable devices themselves have any security features at all.
The MCT VNC server only provides minimal single-password based security access. Separating the control
LAN from the office LAN using a firewall would increase security and only allow control access that is based on
a combination of IP source address, destination address, and port number. This is by no means completely
“hacker-proof”, but it should keep the well-meaning co-workers out.
Another hazard is connecting consumer
“plug and play” devices to your control LAN. A printer for example,
might flood the network with traffic in a
“broadcast storm” as it tries to self-configure or advertise its presence
to all nodes on the network. Faulty devices, for example defective NIC cards, can transmit large amounts of
bad packets (i.e., runts, which are abnormally short Ethernet frames) into your network. Using switches instead
of hubs will limit the effect of such problems.