Creating a New Binary Message Using an ASN.1 Schema

A new empty message can be created by using an ASN.1 schema file as the template using the Empty Message command.

1. Click the File option from the File Operations toolbar.

2. Select the New Message > Empty Message option to open an Empty Message creation wizard (Ctrl + E for a shortcut):

3. The Create Empty ASN.1 Message Wizard dialog window will be displayed:

This dialog will present two types of ASN.1 Standard Categories to choose from:

• 1997 / 2001 ASN.1 Standard: this option will be selected by default.
• 1990 ASN.1 Standard: if ASN.1 files are using MACRO definitions, then this option should be selected.

It will also ask for selection of the ASN.1 encoding rules to be used:

• BER/DER - for the Basic or Distinguished Encoding Rules
• PER (aligned) - for the Packed Encoding Rules, aligned variant
• PER (unaligned) - for the Packed Encoding Rules, unaligned variant

4. The Add button next to the ASN.1 Files selection box will allow the user to add the ASN.1 files required to create a new message. The Add button next to the Include Directories selection box allows specification of include directories for specifications that import items from other ASN.1 specifications.

5. After adding at least one ASN.1 schema file, the Next button will be enabled. ASN1VE will then try to compile the selected ASN.1 files. If the ASN.1 files have syntax errors, then the following dialog window will be displayed:

Pressing the OK button will dismiss the window. Details on the specific errors are output to the error log window in the lower right area of the display:

The user must then correct the syntax errors in the ASN.1 file and then the operation may be retried.

If the validation is successful, then the following dialog window will be displayed:

6. In this step, Display Possible PDU Types and Display All Types radio boxes will be displayed with the list of module names in the selected ASN.1 specifications. Each module will contain a list of type names in that module.

The Display Possible PDU Types button selection will show only those types that are most likely to be used for a new message. This is defined to be all types in the module that are not referenced by any other types. If no types meet this criteria, then no types will be displayed in that module's type list.

The Display All Types selection will display all of the types for each module.

Note: The Finish button will be enabled after selecting the PDU type. On pressing this button, ASN1VE will create a new message using the selected PDU type with all data values set to empty (zero) or to any default values defined in the schema. In the case of PER, elements that have constraints will be set to a value within the constraint range. The message view will be switched to element view and that will allow the user to start message editing and to populate the fields with data.