---
name: "msts"
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/msts"
---

# msts(4)

Meinberg Standard Time String timedelta sensor

## NAME

**msts** – Meinberg Standard Time String timedelta sensor

## SYNOPSIS

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

## DESCRIPTION

This line discipline interfaces serial Meinberg devices.

The line discipline is enabled by the following sequence:

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

The byte stream is unaltered by the line discipline which maintains a timedelta sensor using the MSTS data. The timedelta sensor will appear as msts\* 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.

The Meinberg radio clocks use the following default baudrates:

- GPS-receivers (external and PCI, COM0)

  19200/8N1

- GPS-receivers (external, COM1)

  9600/8N1

- DCF77-receivers (external)

  9600/7E2

- DCF77-receivers (PCI)

  4800/8N1

## 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. Some receiver units need PPS to be manually turned on.

The status of a second sensor is used to report the status of the device itself:

- OK

  The clock is synchronized, e.g. a GPS receiver has a fix.

- WARN

  The device issued a warning condition, e.g. a GPS receiver has no fix.

## SEE ALSO

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

## HISTORY

The **msts** interface first appeared in OpenBSD 4.3.

## AUTHORS

The **msts** line discipline was written by Marc Balmer ⟨*mbalmer@openbsd.org*⟩.