MATLAB: PacketLoss on UDP communication between xPC target and host computer

udpxpc target

Dear all,

I use UDP blocks from xPC target library to send and receive data between xPC and host pc.

The Receive block has two output ports. The first port is the output of the received data. The second one is a flag indicating whether any new data has been received. The second one reflects the "pacakgeLoss".

During the implementation, the comunication (send and recieve 2 "doubles" data at 100Hz) suffers a great "packageLoss", about 20%. The network is LAN and very fast. I 'd like to ask whether this the nature of UDP with a great packageLoss?

I know I could use 'feedback' method introduced by the UDP demo from matlab help to re-send the lost package. However it does not improve the packageLoss fundamantally.

Does anyone have any idea about this? Thanks.

Lily

Best Answer

If you are using full duplex with a proper cable, and any switches involved are decent, and these are the only devices on the network, and if your transmission rate is not greater than what the target can keep up with, and if your ethernet cards are real ethernet cards and not very cheap ones that use the main CPU to run them -- then you should expect UDP packet losses less than 0.01% .

It isn't difficult to get ethernet cards and cables and switches that will have quite acceptable loss rates, but the lowest priced products can be trouble.

Related Solutions

MATLAB: How does the Raw Ethernet frame looks like w.r.t xpc target example “Real Time Transmit and Receive over Ethernet”

Your understanding is accurate. The Ethertype in the example is the length of the data packet. this is because the parameter 'EtherType' in block 'Create Ethernet packet' is set to '0' which is used to indicate that the EtherType field should be set to the length of data. This is as per IEEE 802.3. The Raw Ethernet example does not contain ARP, IP etc.

The best way to analyze this is by sniffing the packets using Wireshark.

MATLAB: How to perform target-to-target Real-Time UDP communications, in xPC Target 5.1 (R2011b)

There is no specific example of how to do this in the official documentation at this time.

Please see the attached resolution files, "dxpcUDP2Tgt1TxReal.mdl" and "dxpcUDP2Tgt2RxReal.mdl", for an example of target-to-target Real-Time UDP communications using the Real-Time UDP blockset from the xPC Target library. To use this example, it will be necessary to configure the Network Configuration and UDP Send/Receive blocks to be specific to the given hardware situation.

Make sure that the card that you specify for target-target real-time UDP is NOT the same card that is used for host-target communication. To determine which card is used for host-target communications, please do the following:

1) Execute the following command to get a list of all of the installed PCI devices on the target system:

getxpcpci('all')

2) Boot the target machine. When you first boot the machine, before you load a model, the target machine will display information that includes the PCI slot and bus number for the card that is being used for host-target communications. Make sure that you do NOT use this card for target-target UDP, use one of the other installed cards instead.

Best Answer

Related Solutions

MATLAB: How does the Raw Ethernet frame looks like w.r.t xpc target example “Real Time Transmit and Receive over Ethernet”

MATLAB: How to perform target-to-target Real-Time UDP communications, in xPC Target 5.1 (R2011b)

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