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Operation
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Prodigy/CME PC/104 User’s Guide
2
2.5.4 Ethernet Communications
The Prodigy/CME PC/104 cards support two different Ethernet protocols, TCP (Transmission Control Protocol)
and UDP (User Datagram Protocol). TCP is typically used for secure communications to the card, while UDP is
typically used for non-critical applications such as data logging, or for the Pro-Motion console window. See
Section
2.4.6, “Debug Console Window,” on page 44 for more information on the C-Motion Engine console window.
The table below shows the range and default settings for the Ethernet controller of the Prodigy/CME PC/104 card:
Each physical hardware device on an Ethernet network is assigned one IP address, however, a given IP address can
have multiple ports. This is useful because it allows user application code running on the C-Motion Engine to open
up multiple peripheral connections by using different port numbers.
To create an Ethernet/TCP or Ethernet/UDP peripheral conversation, the IP Address and port are specified in the
PRP message body of an
Open command sent to the Device resource. To transfer messages via this peripheral
connection the PRP actions
Send
and
Receive
sent to the
Peripheral
resource are used.
After a reset or at power-up, the card retrieves default information for the Prodigy/CME PC/104 Ethernet port. To
change these default values, the PRP
Set command is sent to the Device resource. See Section 2.6.3, “Setting Card
Defaults,” on page 50 for a description.
For detailed information on PRP action formats and function, refer to the Prodigy/CME Programmer’s Reference.
2.5.4.1 TCP Connection Keep-Alive
All prodigy/CME card TCP connections, including the PRP communications port, use a ‘keep-alive’ mechanism to
detect whether a connection is still valid.
The keep-alive mechanism is a standard part of the TCP protocol specification, and is useful for preventing the prod-
igy/CME card from leaving connections open if the host has not properly closed a connection. This may occur, for
example, if the host has been physically disconnected, or otherwise stops functioning.
The default keep-alive parameters for the Prodigy/CME cards are:
The idle time is the amount of time after the last message on the port that must occur for a ‘keep-alive’ message to be
sent. When sent, the keep-alive message requests the host connection to acknowledge that it is still functioning prop-
erly. If it provides this acknowledgment, the
idle time counter is reset to 0. If it does not, a second ‘keep-alive’ message
will be set after the interval time , and this will be repeated a total of retry count number of times. If the host ultimately
does not correctly respond, the Prodigy/CME connection will automatically be closed.
By convention, the 32 bit values for IP Address, Net mask, and Gateway are shown in Dotted Quad Notation. In
this notation each of the four numbers are separated by dots, and denote a decimal value for each byte of the four
byte word
Parameter Range Default
IP address 0.0.0.0 – 255.255.255.255 192.168.2.2
Net mask 0.0.0.0 – 255.255.255.255 255.255.255.0
Gateway 0.0.0.0 – 255.255.255.255 0.0.0.0
PRP Listen TCP Port 0 - 65,535 40100
Parameter Range Default
idle time 0 - 65,535 seconds 60 seconds
interval time not settable 30 seconds
retry count not settable 2