13 | GigE interface functionality Baumer
232 Operating Manual VCXG.2 / VCXG.2.XC / VCXG.2.I / VCXU.2 | V1.2
13.5.4 Force IP (Static IP)
Faults in operation can lead to connection errors between PC and camera.
In this case,Force IP (Static IP) may present a final solution. The Force IP feature will transmit
IP address and subnet mask to the camera's MAC address. These settings are sent without ver-
ification and immediately applied by the client. They remain valid until camera power off.
13.6 Packet Resend
Since the GigE Vision
®
standard requires UDP - i.e. stateless user datagram protocol - for data
transmission, there must be a feature to secure "lost" data.
A resend request is initiated if one or more packets are corrupted during transmission and sub-
sequently discarded - due to incorrect checksum.
Thee are three scenarios:
Standard case
In smooth data transfer, all packets are transferred from the camera to the PC in correct order.
This is assumed to be true at more than 99%.
Error 1: Lost packets in the data stream
If one or more packets are lost within the data stream, this is identified by packet number n be-
ing not followed by packet number (n+1). In this case, the application transmits a resend re-
quest (A). After this request, the camera transmits the next packet and again the lost packet (B).
In our example, packet no. 3 was lost. This error is detected on packet #4 triggering the resend
request. The camera then transmits packet No. 5, followed by resending packet No. 3.
Error 2: Lost packet at the end of data stream
In case of a failure at the end of the data stream, the application waits for incoming packets for
a predefined time. After this time has elapsed, the request to resend is triggered and the "lost"
packets are resent.
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