RSVSwitch - Video Switcher and Video Sequencer Support FAQ

Troubleshooting

Video cable distance
The RSVSwitch is a basic electronic video switch that does not regenerate video signals. It does provide some amplification of signals. Introducing additional connectors into a video line will attenuate the signal as will longer cable runs. The switch amplifies signals to compensate for the signal loss of the cabling and connectors. Generally speaking, the shorter the cable runs, the better the video quality will be. Always use shielded cables. A video amplifier can be used to boost the video signal to compensate for signal drops over long distances. Runs of up to 100ft will normally not require an amplifier. Cheap cameras may have some difficulty driving long distance runs. One way to get around longer distances for video sources is to centrally locate the RSVSwitch between all the cameras and use a longer serial cable to connect to the PC. Serial lines are normally more forgiving over longer distances. The RSVSwitch is designed to allow the serial RJ45-to-DB9 serial cable to be extended using shielded serial cable or shileded network cables.

Changing the length of the serial cable
The RSVSwitch ships with a shielded cable certified to comply with FCC emmissions guidelines. You can extend this cable using standard serial extension cables. You should use a properly shielded cable or install EMI ferrites on the cable to control high frequency emissions. The RSVSwitch is certified for emissions compliance only with shielded or suppressed cables. Extended runs are possible, up to hundreds of feet depending on the power capability of your serial port and the type of cable you are using. Custom low resistance serial cable or a signal booster allow for further distances. These solutions are beyond the scope of this document.

You can also extend the serial cable using a Cat5E shielded network cable and a shielded coupler. To prevent electrical interference, always use shielded cables.

Camera compatibility
The RSVSwitch has been tested with a variety of NTSC video cameras for compatibility. Some of the lower end cameras may exhibit high brightness output when used with the RSVSwitch. Typically, color cameras work well, but some of the black and white pinhole cameras have high gain outputs that may overdrive your capture card, causing the image to be too bright. You will normally be able to correct for this by adjusting the brightness for individual cameras. Video monitors and TVs generally do not experience this problem. Use a video attenuators on the cameras that exhibit this problem.

The RSVSwitch doesn't respond to the serial port
Most problems encountered with communication come down to improper settings in the software on the computer side. You must set your computer for N-8-1, no parity, 8 bits, 1 stop bit. You must also have the PC set for the correct COM port. Verify all of your settings and check your cabling. If the switch still does not respond, try connecting at 2400bps, 4800bps, 9600bps, and 19200bps. The switch should respond to a menu request ("?") at one of the speeds. If it still does not respond, check your cables again. If you have replaced the cables shipped with the switch, try the original cables. In some cases, COM port conflicts may cause HyperTerminal under windows to be unable to receive data on the serial port. Shut down other serial applications including hotsyncing apps, close HyperTerminal and restart it and try again. Verify that you have plugged the switch into the proper COM port on your computer.

Try unplugging the video switch from all of the cables, wait two minutes, and plug it back in. This will allow any transient settings to clear and reverts the device back to the saved settings. If this still doesn't work, set the device to factory defaults (send "FWR").

The serial port is sending garbage characters or is partially readable.
Check your cabling. You must have a grounded and shielded connection between the RSVSwitch and the PC. If the grounds are not connected, the serial data will be corrupted. If the cables are not properly shielded, noise may occur on the serial line.

The switch keeps sending numbers when I'm connected with a terminal program.
Event feedback is turned on. Every camera change will send a number. Use the "Q" option to disable the numbers.

How do I turn off the device?
The switch is designed to be controlled by the computer. You can turn off video using the "0" option. To completely power down the device, you must unplug the power or use a power strip or other power switching device.

Video shakes, noise or bars appear temporarily when switching
This is a function of your video capture card. Most cards have a settling time while they reestablish video sync when switching between cameras. Elimination of this effect requires high speed sync locking or that all of the video sources be tied to the same video sync source. This is an expensive feature typically found only in professional grade multiple source systems. If you experience more than a second of distortion, are unable to get a sync lock when switching, or just want to smooth transistions, try disabling all video and then switching. This can accomplished by sending the switch a "0" (zero) and then the camera code ("1"-"4").

Video flares or dims when switching
This is a side effect of how your video capture card processes varying light levels. When switching from a high light source to a low light source, the capture card may need to adjust the gain setting. This results in a short delay while the input level is balanced. Using cameras at similar lighting levels should eliminate the video effects. This effect is not typically seen on video monitors. You may also be able to use a video attenuator to lower the input level of cameras that are flaring.

The switch changes modes and starts scanning.
This could be caused by line noise or by extra characters or messages on the serial line. If you have connected to the switch's serial port to something other than a computer with Hyperterminal, that device may send a status message to the serial port when it boots up or when other events occur. Those messages could cause the video switch to changes modes. e.g If your controller sends "RS-232 serial controller online", several letters in the message will be interpreted as commands by the switch. To resolve this, disable the status messages. If you cannot disable the messages, you may be able to script around them. For instance, if your device is switching to scan mode, you can override this by sending a camera selection periodically or by adding M to the camera select commands to force manual mode. So to switch to camera 1, send "1M". This will switch and set manual mode at the same time.

Firmware upgrades
RevC: Revision C changes the sensor inputs from active low to active high. This increases compatibility with third party sensors.

Firmware upgrades from RevB to RevC are handled thru a ship and return program. The cost is $10, which includes return shipping. You can send your switch in for upgrade and it will be upgraded and returned (normally within one day).

Known Bugs
There are no known bugs.

This document last revised 11/14/2008