01. Concerns with Exporting AutoPIPE Batch (*.NTL) file and then Opening that *.NTL file again in Au

Area: Import / Export
Original Author:Bentley Technical Support Group
Date Logged
& Current Version
Feb. 2016


What are the concerns with saving an AutoPIPE model as an AutoPIPE Batch (*.NTL) file and then opening that *.NTL file in AutoPIPE?

TR Number: none
Product: AutoPIPE
Version: all
Area: General
Problem ID#: 79405


The process of saving an AutoPIPE model (*.DAT) file to an AutoPIPE Batch (*.NTL) file, and then opening the *.NTL file in AutoPIPE to create a new *.DAT file is referred to by us as "round tripping a model"

Information is saved to the AutoPIPE model *.DAT file in a database format with very specific settings. The AutoPIPE BATCH file (*.NTL) is data written out from the database into another specific formatted text file (see AutoPIPE help for "Command Card Reference" details about how each component is formatted in the NTL file). 

When the NTL file is opened in AutoPIPE, the model is created based on the NTL file settings. Because of translating data from DAT to NTL back to DAT, any missing data will assume its default settings and all data referenced to a library file is refreshed. This is why it is VERY VERY IMPORTANT to follow this procedure:

1. Open original AutoPIPE model DAT file (Test.DAT)

2. Create a complete Model Input listing report with all sub reports enabled. 

3. Run an analysis.

4. Select Results> Output report> ensure all sub reports are checked ON.

Recommend only "Include Description" and "Model Listing" options be turned ON, with all other options turned OFF.

5. Next, select File> Save As > AutoPIPE Batch (TEST-1.NTL)

6. Select File> Open> AutoPIPE batch (*.NTL)> select file (ex.Test-1.NTL)

7. READ and understand any reports that were automatically displayed (ex. CHK, MSG, etc..)

8. Repeat Steps 2-4 to generate Model Input listing report and complete Output report using the new model.

9. Use an application (i.e., Ultra Compare, Beyond Compare (free on internet)) to compare complete output reports of the original file to the newly created file to CLEARLY see the differences.

10. IN MOST CASES, the new DAT file will need to be updated to match the original DAT file.

Again, it is very important to perform this process of file comparison and/or to thoroughly review the new DAT file to be sure of model settings.


1. Round tripping a model may reset some items to their default settings, therefore check all settings in the model especially: General Model options, Edit model options, and Results Model options are correct.

2. Because this process rewrites the model database, this process can be used to filter / fix a model that has some peculiar unexplained issues occurring. 

3. Another method to Filter / Fix a model is to create a new model with the same General model options as the original affected model. Than IMPORT the affected model into the new model.

4. An added advantage of round tripping a model, all node point names, segment, support ids, etc.. are renumbered starting from the beginning. 

5. If model has rigid options, save the model to Batch (*.ntl), open the NTL file in any text editor, search the file for all rigid command card data, delete the rigid data, save the file, and open in AutoPIPE. Perform this task until issue has been fixed in a future version of the program (1113136).

6. In some cases the round trip model has a number of additional node points that are easily identified because they contain non-alpha / numeric characters (ex. P%%1, P%$K). These node points should be manually deleted from the round tripped model.

See Also

Why are the Results different with similar input in AutoPIPE?

Export AutoPIPE Batch (NTL)

Bentley AutoPIPE