Find outputs that drive the same net

Two outputs on one wire fight each other. When one gate drives high and the other drives low, the net ends up somewhere in between and, in real hardware, a large current flows through both output stages. Ohmforge's Output conflict review looks for exactly this mistake. It sits in the Connectivity review dialog, below the connection findings.

Create a conflict on purpose

Open the Logic half-adder template. U1 is an XOR gate that drives the SUM label, U2 an AND gate that drives the CARRY label.

1. Press W (or choose Wire (W) in the toolbar).
2. Click the output pin at the right end of U1, then the output pin at the right end of U2. Clicking a pin finishes the wire.

Both outputs now sit on one net. Nothing looks wrong yet: the schematic is still tidy and every pin is connected.

Run the review

Choose Connectivity review (the check-mark button after Power switch, or Simulate → Connectivity review…). The upper part of the dialog shows the usual connection findings. Because SUM and CARRY are now one node, it also reports that the net has several labels.

Scroll to Output conflict review. Three numbers summarise it:

• Output pairs sharing a net: 1.
• Pins with a catalogued role: 6. These are the two inputs and the output of each gate.
• Unclassified pins: 20. Switches, resistors, LEDs, logic probes and the source have no catalogued role.

The finding reads Outputs U1.Y and U2.Y share a net. with the net name and both grid positions. Choose Show U1 or Show U2: the dialog closes, and Ohmforge selects that gate and centres it on the schematic. Press Ctrl+Z to remove the wire and run the review again. It now reports No output conflicts found within the classified roles.

Read the unclassified count first

The review knows pin roles only for the built-in AND, OR, NAND, NOR, XOR and NOT gates and the comparator. Every other pin is counted as unclassified, including the comparator's supply pins. Unclassified pins are never assumed to be safe; they are simply not checked. A circuit built from transistors and op-amps can therefore show zero conflicts because almost nothing was classified. The sentence under the counts says how many pins were skipped.

A few rules worth knowing:

• Net labels connect, so two outputs labelled SIG in different corners of the sheet count as a conflict even without a wire. Label names are case-sensitive; 0 and GND join the ground net in any letter case.
• Three outputs on one net give three pairs. At most 100 pairs are listed, and a note tells you how many more were found.
• Net names such as N002 can change after edits. Use the part and pin names to find the problem.

The review does not check power, logic levels, ratings, undriven inputs or open-drain outputs. Simulate the circuit as well.

Run the same check from a script

Scripts and AI agents can run the review as Schematic Output Conflict Review: ohmforge-output-conflict-review in the JSON API (POST /api/v1/tools/ohmforge-output-conflict-review/calculate) or ohmforge_output_conflict_review over MCP. Send the saved project as text in the project field. The result contains classifiedPins, unknownPins, totalConflicts, omittedConflicts and a conflicts list. Each entry names both terminals with part, pin and grid point, plus the net. The tool accepts native .ohmforge.json projects up to 200 KB. The existing ohmforge-connectivity-review tool keeps its output unchanged.