Specifications

Table Of Contents
Version 1.1 rev Jan 2013
Page 96
iXon Ultra
Troubleshooting
5.4 - CAMERA HIGH FIFO FILL ALARM
On some systems, it has been observed that a camera will stop acquiring after approximately 1 - 10 seconds. When this
occurs it has always been caused by insufcient USB bandwidth. The camera includes a buffer (FIFO) to overcome any
short term bandwidth reductions, however, sustained insufcient bandwidth will always cause the buffer to overow –
regardless of what size of buffer is used. The PC should be able to cope with a sustained USB data transfer of equal to
or greater than 40 Megabytes/second. Modern machines should all be able to cope with this.
Two causes of USB 2.0 Cameras stopping acquisition have been found thus far:
1) Power saving settings in the PC BIOS. All PC systems are now required to be shipped in power saving mode (under
EUP legislation). In the Dell T5500 models (and likely all new systems) there is a setting in the BIOS called “C States
Control”. Ensure this is disabled, as this saves power by sacricing USB bandwidth. Other PC manufacturers may have
similar settings.
2) Sharing USB bandwidth with other devices. An example of this is using USB to RS-232 adapters. These
signicantly reduce the USB bandwidth available, to the point where the camera can not continuously transmit images.
This occurs even if the software that uses these USB to RS-232 devices has not been started.
This problem can only be overcome if the PC being used has dual USB Enhanced Host Controllers. Dell 760 machines
have ICH10 family southbridges, which have two “Enhanced Host Controllers” (EHC) . Each one of these is able to
receive the maximum USB rate from a Clara/iXon Ultra (assuming there is sufcient RAM, CPU etc to process the data).
If the machine has only one EHC it may not be possible to operate a Clara/iXon Ultra and any other devices that require
signicant USB bandwidth.
To ensure the Camera has full USB bandwidth it is best to ensure it does not share its EHC with any other High
Bandwidth USB devices i.e. do not connect the USB to RS-232 adaptors into the same EHC. These two EHCs can be
shared between the front and the back USB ports of the PC and so it may be advantageous to map which physical USB
port is associated with which EHC.
5.5 - USE OF MULTIPLE HIGH SPEED USB 2.0 I/O ON ONE CAMERA
On PCs with two or more EHCs it may be benecial to map each physical USB connector to it’s EHC. Below shows
how to do this on a Dell T5500 PC using a (modern) USB memory stick and the application “UVCView.x86.exe” from
Microsoft.
USB devices can be High Bandwidth (Fastest), Full Bandwidth or Low bandwidth (e.g. mouse, keyboard). A modern
USB stick will be High Bandwidth.
Run UVCView.exe to monitor the USBs ports usage.