Lesson 5.10 – Automating Title Blocks with AutoLISP

🗂️ Lesson 5-10 – Automating Title Blocks with AutoLISP

Learn how to insert a block with attributes and fill in its values automatically.

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📚 What You’ll Learn

By the end of this lesson, you’ll be able to:

• Insert a block containing attributes using AutoLISP
• Supply values for each attribute programmatically
• Automate repetitive title block updates across sheets
• Understand how attribute tags work with entmake and command

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🧠 Why It Matters

Title blocks are vital for identifying drawing details—but filling them in manually across dozens of sheets is inefficient. AutoLISP makes it possible to insert and populate title blocks with a single command, reducing errors and saving time.

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🛠️ Tools You’ll Use

Function	Purpose
command	Inserts the block into the drawing
entget	Retrieves the block reference data
entnext	Steps to the next entity (e.g., attached attributes)
entmod	Modifies attribute values
entupd	Forces drawing update

🧭 Lesson Structure

1️⃣ Prerequisite: Block with Attributes

Your title block must already be defined in the drawing (or as an external .DWG) and must contain attributes—text fields tied to tags like "DRAWNBY", "DATE", "PROJECT".

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2️⃣ Insert the Block Using command

Example inserting a block named "TITLEBLOCK" at the origin:

(command "INSERT" "TITLEBLOCK" '(0 0 0) 1.0 1.0 0.0)

• (0 0 0) = Insertion point
• 1.0 = Scale X and Y
• 0.0 = Rotation angle

✅ Use double quotes around block name if it contains spaces.

3️⃣ Fill in Attributes

After insertion, use entnext to walk through attached attributes.

(defun c:filltitleblock ( / blk ent tag val )
  (setq blk (entlast)) ; assume last inserted is the block
  (setq ent (entnext blk)) ; move to first attribute

  (while ent
    (setq tag (cdr (assoc 2 (entget ent)))) ; tag name
    (cond
      ((= tag "DRAWNBY") (entmod (subst (cons 1 "Jane D.") (assoc 1 (entget ent)) (entget ent))))
      ((= tag "DATE")    (entmod (subst (cons 1 "2025-05-29") (assoc 1 (entget ent)) (entget ent))))
      ((= tag "PROJECT") (entmod (subst (cons 1 "Warehouse Reno") (assoc 1 (entget ent)) (entget ent))))
    )
    (entupd ent)
    (setq ent (entnext ent)) ; next attribute
  )
  (prompt "\\nTitle block attributes updated.")
  (princ)
)

✅ Lesson Checklist

Task	Completed
Inserted a block with command	☐
Verified it has attributes with defined TAGs	☐
Used entnext to step through attached attributes	☐
Replaced attribute values using subst and entmod	☐

📌 Quick Tips

Tip	Why It Helps
Always test for the correct block name	Avoids inserting the wrong object
Attribute tag names are case-sensitive	"DATE" is not the same as "date"
Use entnext carefully	Attributes appear sequentially after the block
Use entupd after entmod	Ensures screen refresh

🧩 Real-World Applications

Use Case	Attribute Tag Examples	Purpose
Insert & populate new sheets	SHEETNO, REV, DATE	Batch drawing generation
Update old projects	PROJECT, CLIENT, DRAWNBY	Standardize documentation
Customize templates	TITLE, DWGNO, SCALE	Adapt blocks for specific jobs

📁 Files and Resources

File / Resource	Description
insert_titleblock.lsp	Script to insert a title block at origin
fill_attributes_example.lsp	Script to populate attributes for last inserted block
attribute_tags_template.docx	Editable list of typical title block tags and uses

📖 Review Table

Function	Description	Example
command	Inserts a block	(command "INSERT" "TITLEBLOCK" '(0 0 0) ...)
entget	Retrieves entity data	(entget ent)
entnext	Moves to next entity (e.g., attribute)	(entnext blk)
subst	Replaces value in DXF list	(subst (cons 1 "John") (assoc 1 dxf) dxf)
entmod	Applies the changes	(entmod dxf)
entupd	Refreshes the visual result	(entupd ent)