Scripts/AutoCAD/MCM_Installer_drawing/SPLITTER_LOGIC.md

Splitter Detection Logic in IO.lsp

Overview

The script decides whether to create a single cable or two cables + splitter based on the DESCA values in each pair.

Decision Flow

Step 1: Check if both DESCA values are filled

If val1 = "" OR val2 = ""
  → Go to Case 2 (single value handling)
Else (both val1 and val2 have values)
  → Go to Case 1 (pair handling)

Step 2: Case 1 - Both values filled (Pair handling)

For FIO/FIOH blocks (special handling at lines 318-427):

SPLITTER CREATED if:

• Both values contain "TPE" AND they're different names (e.g., TPE2 vs TPE3)
• One contains "RCV" and other contains "SND" (or vice versa)

SINGLE CABLE if:

• None of the splitter conditions above match → default to single cable

For all other blocks (VFD, SIO, etc. at lines 432-445):

SINGLE CABLE if values match any of these patterns:

• Both contain "SEL"
• Both contain "DPM"
• Both contain "VFD" AND both contain "STO"
• One contains "_PB" and other contains "_PB_LT" (pushbutton + light)
• Both contain "BCN" (beacon stack)
• Both contain "EPC"
• Both contain "SSP"

TWO CABLES + SPLITTER if:

• None of the single-cable conditions match → default to splitter

Summary Table

DESCA1 Pattern	DESCA2 Pattern	Result
*_SEL*	*_SEL*	✅ Single cable
*_DPM*	*_DPM*	✅ Single cable
*VFD*STO*	*VFD*STO*	✅ Single cable
*_PB*	*_PB_LT*	✅ Single cable
*_PB_LT*	*_PB*	✅ Single cable
*BCN*	*BCN*	✅ Single cable
*EPC*	*EPC*	✅ Single cable
*SSP*	*SSP*	✅ Single cable
*TPE* (different)	*TPE* (different)	⚠️ SPLITTER (FIO only)
*RCV*	*SND*	⚠️ SPLITTER (FIO only)
*SND*	*RCV*	⚠️ SPLITTER (FIO only)
Anything else	Anything else	⚠️ SPLITTER

Key Code Locations

• Lines 318-332: FIO/FIOH splitter conditions (TPE pairs, RCV/SND pairs)
• Lines 432-445: All other blocks - single cable conditions
• Lines 505-519: Default ELSE branch - creates splitter for unmatched pairs

Example Scenarios

1. Beacon stack (BYDC_6_BCN1_A + BYDC_6_BCN1_H):

   • Both contain "BCN" → ✅ Single cable (line 443)

2. Pushbutton + light (*_PB + *_PB_LT):

   • Pattern match → ✅ Single cable (lines 440-441)

3. TPE pairs (*TPE1 + *TPE2):

   • For FIO blocks → ⚠️ Splitter (lines 322-324)
   • For other blocks → ⚠️ Splitter (default)

4. Two different devices (e.g., *DEVICE1 + *DEVICE2):

   • No pattern match → ⚠️ Splitter (default)