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Ports are used to direct traffic to the right application once it gets to the right IP address. The UDP eSCL port in
our drives is 7775. To send and receive commands using TCP, use port number 7776. You’ll need to know this
when you begin to write your own application. You will also need to choose an open (unused) port number
for your application. Our drive doesn’t care what that is; when the first command is sent to the drive, the drive
will make note of the IP address and port number from which it originated and direct any responses there. The
drive will also refuse any traffic from other IP addresses that is headed for the eSCL port. The first application to
talk to a drive “owns” the drive. This lock is only reset when the drive powers down.
If you need help choosing a port number for your application, you can find a list of commonly used port num-
bers a
.
One final note: Ethernet communication can use one or both of two “transport protocols”: UDP and TCP. eSCL
commands can be sent and received using either protocol. UDP is simpler and more efficient than TCP, but TCP
is more reliable on large or very busy networks where UDP packets might occasionally be dropped.
Option 1: Connect a Drive to Your Local Area Network
If you have a spare port on a switch or router and if you are able to set your drive to an IP address that is com-
patible with your network, and not used by anything else, this is a simple way to get connected. This technique
also allows you to connect multiple drives to your PC. If you are on a corporate network, please check with
your system administrator before connecting anything new to the network. He or she should be able assign you
a suitable address and help you get going.
If you are not sure which addresses are already used on your network, you can find out using “Angry IP scanner”,
which can be downloaded free from
ut be careful: an address might
appear to be unused because a computer or other device is currently turned off. And many networks use dy-
namic addressing where a DHCP server assigns addresses “on demand”. The address you choose for your drive
might get assigned to something else by the DHCP server at another time.
PC
NIC
SWITCH
or
ROUTER
LAN
DRIVE
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STM23 Hardware Manual
920-0021F
2/14/2012