---
name: "endrun"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/endrun"
---

# endrun(4)

EndRun Technologies native time-of-day message timedelta sensor

## NAME

**endrun** – EndRun Technologies native time-of-day message timedelta sensor

## SYNOPSIS

**pseudo-device endrun** \[*count*\]

## DESCRIPTION

This line discipline interfaces serial EndRun Technologies devices.

The line discipline is enabled by the following sequence:

```
#include <sys/ioctl.h>
int ldisc = ENDRUNDISC, fildes; ...
ioctl(fildes, TIOCSETD, &ldisc);
```

The byte stream is unaltered by the line discipline which maintains a timedelta sensor using the EndRun data. The timedelta sensor will appear as endrun\* in the list of sensors and the delta (in nanoseconds) between the received time information and the local time can be accessed through the [sysctl(8)](/sysctl/8.md) interface.

## SENSOR STATES

The quality of the timedelta is reported as the sensor status:

- OK

  The time information is valid. The timedelta is safe to use for applications like [ntpd(8)](/ntpd/8.md).

- WARN

  The attached receiver has been indicating a warning condition for at least the last ten minutes. The timedelta should be used with care.

- CRITICAL

  tty timestamping has been turned on but there is no PPS signal present or the receiver indicated a warning condition for at least the last twenty minutes. Check your hardware.

The status of a second sensor is used to report the status of the device itself using the Time Figure Of Merit (TFOM) character:

- OK

  The clock is synchronized. TFOM is 6-8.

- WARN

  The clock is synchronized and the time error is greater than 10ms or the clock is in the unsynchronized state. TFOM is 9.

- CRITICAL

  The TFOM is invalid.

## SEE ALSO

[tty(4)](/tty/4.md), [ldattach(8)](/ldattach/8.md), [ntpd(8)](/ntpd/8.md), [sysctl(8)](/sysctl/8.md)

## HISTORY

The **endrun** interface first appeared in OpenBSD 4.6.