VB6 Serial Port Communication

Inspect the implementation

• Record Settings, Handshaking, InputMode, RThreshold and InBufferSize.
• Determine whether OnComm assembles partial frames safely.
• Keep binary traffic as bytes rather than text conversions.
• Trace timeouts, retries and device-state transitions.
• Check hard-coded COM numbers and adapter/control-line behavior.

Diagnose by layer

Compare wire capture with bytes received by VB6. Identical wire traffic but changed event chunking indicates buffering/component behavior; corrupt wire traffic indicates framing, cable or interface issues.

Use traffic capture, USB adapter assessment, framing diagnosis and the VB6 pillar.

Provide source, MSComm settings, raw captures, adapter/driver and timing-sensitive workflow.