Hi again Lilian,
Based on the files you supplied it appears that the DCD magic number has indeed changed (from 84 to 164) for DCDs from CHARMM v33 (and presumably later).  A new magic number typically indicates that the file format is no longer compatible with files with the old magic number, and that is in fact the case here.  If I change Chimera's DCD-reading code to just treat 164 as if it were 84, other error checks fail.  From my tests it also appears that VMD 1.8.7 can't read the new-format DCD either.
Since the new format is undocumented AFAICT, I will be getting in contact with Dr. Karplus to see if I can access CHARMM's DCD-writing code (which isn't free) in order to add the ability to read the new DCDs to Chimera.  I'll keep you in the loop on that.

--Eric

On Apr 26, 2010, at 11:11 AM, Eric Pettersen wrote:

Hi Lilian,
It means that your DCD file doesn't start with the proper "magic number" that all valid DCD files are supposed to contain.  Perhaps if you sent me your trajectory files (directly, not via the list!) I could provide more useful information.  If they are too big for email, you could FTP them to one of our servers.  Let me know if you need/want to do that.

--Eric

                        Eric Pettersen
                        UCSF Computer Graphics Lab
                        http://www.cgl.ucsf.edu

On Apr 23, 2010, at 1:37 AM, Lilian OLIVIERI wrote:

Hello,

I'm having trouble using MD/Ensemble analysis tool.
When I try to check a MD trajectory generated by CHARMM (version C33b1), I
get a "DCD format error 1" message.

Here is the Reply Log:

MDTools 1.2 Exp (2005-08-20) by James Phillips.
Trajectory.DCD.MDToolsMarch97.md.help() for more info.
- HomoCoord 1.3 Exp (2005-08-20)
- Constants 1.1 Exp (2004-05-17)
- AtomGroup 1.4 Exp (2007-02-07)
- local 1.1 Exp (2004-05-17)
Unknown OSTYPE ??? set.  Viewing and plotting are disabled.
- Trans 1.2 Exp (2005-08-20)
- DCD 1.10 Exp (2007-02-07)
- Data 1.2 Exp (2005-08-20)
* THIS FILE IS LANGEVINEEF1.INP.
* USAGE, CHARMM <LANGEVINEEF1.INP >LANGEVINEEF1.OUT.
* RUNS LANGEVIN DYNAMICS WITH EEF1 IMPLICIT WATER.
*  DATE:     3/22/10     10:32:48      CREATED BY USER: lolivier
/labos/lbgm/lolivier/chimera/share/Trajectory/DCD/MDToolsMarch97/md_DCD.py:121:
DeprecationWarning: raising a string exception is deprecated
 raise "DCD format error 1"
Traceback (most recent call last):
 File "CHIMERA/lib/python2.5/site-packages/Pmw/Pmw_1_3/lib/PmwBase.py",
line 1747, in __call__
 File "CHIMERA/share/chimera/baseDialog.py", line 328, in command
 File "CHIMERA/share/chimera/baseDialog.py", line 543, in OK
 File "CHIMERA/share/Trajectory/EnsembleLoader.py", line 92, in Apply
 File "CHIMERA/share/Trajectory/DCD/__init__.py", line 61, in loadEnsemble
 File "CHIMERA/share/Trajectory/DCD/__init__.py", line 71, in loadEnsemble
 File "CHIMERA/share/Trajectory/DCD/DCD.py", line 35, in __init__
 File "CHIMERA/share/Trajectory/DCD/MDToolsMarch97/md_DCD.py", line 121,
in __init__
DCD format error 1
DCD format error 1

 File "CHIMERA/share/Trajectory/DCD/MDToolsMarch97/md_DCD.py", line 121,
in __init__

See reply log for Python traceback.


Is there a quick way to fix this problem?

Thanks for any reply.



--
Lilian Olivieri
PhD student

INSERM UMR-S 665,
DSIMB/LBGM, Faculte des Sciences et Technologies
Universite de La Reunion
15 Avenue René Cassin, BP 7151
97715 Saint Denis Messag Cedex 09
La Réunion, France

Tel: +33 262 938 227 (office)
Fax: +33 262 938 237


http://lbgm.univ-reunion.fr/
http://www.dsimb.inserm.fr/


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the most important.
                            -- Sir Arthur Conan Doyle, "A Case of Identity"
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