<!--
{
  "availability" : [
    "DriverKit: 19.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "SerialDriverKit",
  "identifier" : "/documentation/SerialDriverKit/PD_RS232_S_TXO",
  "metadataVersion" : "0.1.0",
  "role" : "Macro",
  "symbol" : {
    "kind" : "Macro",
    "modules" : [
      "SerialDriverKit"
    ],
    "preciseIdentifier" : "c:@macro@PD_RS232_S_TXO"
  },
  "title" : "PD_RS232_S_TXO"
}
-->

# PD_RS232_S_TXO

The transmit-data signal.

```
#define PD_RS232_S_TXO
```

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)