PDA

View Full Version : CRC errors & Moving output channel strip


Jae Hwan Kim
08-05-2006, 08:03 PM
During show,

1. I got often the CRC Errors.
"The snake Connecting Stage Rack 1 is detecting an unusually high number of CRC errors."
"The snake Connecting Stage Rack 2 is detecting an unusually high number of CRC errors."

Because of that, do I need to use the redundant cables?


2. Is there any way to move an output channel strip? like moving input channel strip.

eddiemapp
08-06-2006, 11:40 AM
I've received these errors before but never had any problems with them.

Sheldon Radford
08-06-2006, 06:08 PM
CRC errors indicate that data wasn't received as expected. Under normal circumstances there should be no CRC errors, so the warning is an indication something isn't quite right and the cause should be investigated. A high number of CRC errors may even result in a momentary loss of audio. Having the redundant snake connection is always a good idea, as the snake system will choose the better of the two signals.

CRC errors are typically caused by one - or a combination - of the following things, in rough order of likelihood:

1) damaged or pinched snake cable
2) damaged snake BNC connections
3) use of an unapproved digital snake cable. Approved cables are listed below.
4) ground differential between stage rack and FOH rack (always feed FOH power from stage and ensure a proper ground)
5) close proximity to coiled, high current AC cables (e.g., coiled backstage or in a cable trunk)
6) some other device is spewing electrical noise in close proximity to the snake.

In general the digital snake system is very robust, and most issues are quickly traced back to damaged hardware. Contact Digidesign Customer Service if the problem persists.

RE: moving outputs. It's not possible to move outputs, but it is possible to copy the channel assignments from one group/aux/VCA to another using the "Replace With Mix From..." feature. Use this to temporarily copy bus assignments to an an unsused bus, and then swap the bus mixes around as desired.

Digital Snake Cable Assemblies:

Customers wishing to build their own digital snake assemblies using copper coaxial cable should adhere to the following cable type and length recommendations:

* SNAKE Connector (x4) BNC Male, 75 ohm
* Cable Type coaxial, 75 ohm

* Max Length 250 ft (76 m):
- Belden 1855A - single conductor
- Belden 7787A - three conductor
- Belden 7788A - four conductor

* Max Length 500 ft (152 m):
- Belden 1694A - single conductor
- Belden 7710A - three conductor
- Belden 7711A - four conductor
- Van damme Cable (VDC) 278-175-00 - single conductor

Sheldon

Jae Hwan Kim
08-08-2006, 01:35 AM
I had CRC errors several times during a show.
CRC Error - stage 1 (http://jhkstudio.com.ne.kr/pics/crcerror1.jpg)
CRC Error - stage 2 (http://jhkstudio.com.ne.kr/pics/crcerror3.jpg)

The digital snake cable(DIGI sent to me) was new one and the error messages were stage 1 & 2.
Therefore, I don't think that the problem was the cable assemblies.



5) close proximity to coiled, high current AC cables (e.g., coiled backstage or in a cable trunk)




I just worried about the digital cable was too long, so I coiled the digital cable next to the stage racks. BUT there wasn't high current AC cables closely.

Sheldon, Do you think that was the reason, coiled the digital cables for stage 1 & 2?


using the "Replace With Mix From..." feature. Use this to temporarily copy bus assignments to an an unsused bus, and then swap the bus mixes around as desired.



I knew it but.... unfotunately there wasn't any unused bus strip in my case.
Do you have a plan to upgrade for the feature?

Sheldon Radford
08-08-2006, 08:44 AM
Hi,

The coiled snake cables themselves likely aren't the cause. Digidesign Cusomer Service will be in touch with you to help resolve this directly.

Here are the types of questions they'll ask:

Do these errors happen all the time, or did they happen only during one show?

If it was only during one show, was there anything different about the show, such as the type of lighting equipment being used, power source, etc.?

Did the errors appear recently? If so, what has changed in the system?

Are any of the BNC connectors loose or damaged?