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AM-10HD / Aug 2008
A M - 1 0 H D G U I
About “Ports” and the AM‑10HD
The AM‑10HD uses a variety of TCP and UDP ports in order to communicate
with the remote GUI. The actual TCP port used depends on the Wheatstone pro‑
cessor model. However, in each case the Wheatstone processor is the “server” and
the PC is the “client.” Wheatstone processors can accept up to four simultaneous
GUI connections to host PC’s.
The AM‑10HD uses TCP port 55895 for “commands” (control adjustments,
etc.) between the host PC and the processor. Metering data does not go over TCP.
Once a TCP connection is established the GUI opens a UDP port and asks
the AM‑10HD to send meter data on that port. The port is typically 60001, but
not always. With UDP ports only one application on a PC may open that port
at a time, and since we do not know what other applications are running on the
PC and we also want to allow more than one GUI to run at a time on any given
PC, the GUI will attempt to open port UDP 60001. If that port cannot be opened,
the GUI will then try port 60002, then 60003, etc., up to 60010. Whichever port
successfully opens first, that port number will be sent to the AM‑10HD and the
AM‑10HD will begin to stream meter data over that UDP port back to the GUI.
Note: If there are two or more GUIs attached to the AM‑10HD then the
AM‑10HD will stream the meter data twice – once for each of the opened port(s)
to the connected GUIs.
If the GUI fails to open any of the 10 UDP ports it will still run and be able to
control the AM‑10HD via the TCP port, but it will not receive any meter data to
display. Therefore if you have a connection that appears to control the processor
just fine but there is no metering displayed on the GUI, check to ensure that there
is no firewall or other blockage to UDP ports 60001 through 60010.
VPN Note: When the IP route between the Wheatstone processor and the host
PC will not permit UDP packets to pass, using a VPN connection can circumvent
this. This is because all IP protocols that will become part of the VPN traffic
get “encapsulated” inside the VPN protocol, making those pesky UDP packets
invisible to the network! The only requirement for making this work is that the
Wheatstone processor needs to be connected to a local PC which will serve as
the VPN host. Other PC’s will connect remotely to this computer utilizing the
VPN protocol.
Another way to connect to the Wheatstone processor when UDP presents
a challenge is to use the second PC as above, but use a program such as VNC
(Virtual Network Connection) between the local and remote host PC’s.
