RUGGEDCOM RS416
Installation Guide
Chapter 1
Introduction
TTL Outputs
5
IRIG-B PWM
IRIG-B time synchronization is an even older, established, inter-device time synchronization mechanism providing
accuracy in sub-milliseconds.
IEEE 1588
IEEE 1588 is designed to provide networked, packet-based time synchronization between different networking
nodes (PTP devices). The RS416 supports PTP v2, which is defined in the IEEE 1588-2008 standard. IEEE 1588 is
designed to fill a niche not well served by either of the two older, dominant protocols, NTP and IRIG-B. IEEE 1588
is also designed for applications that cannot bear the cost of a GPS receiver at each node or for which GPS signals
are inaccessible.
The RS416 only supports ordinary clock mode. An ordinary clock can be configured as either a Grandmaster Clock
(GM) or a Slave Clock (SC) within the master-slave hierarchy.
Every Ethernet port on the RS416 supports IEEE 1588. For more information, refer to
Section 1.3.2
TTL Outputs
The PTP card provides a TTL (Transistor-Transistor Logic) output.
The TTL OUT port supports the IRIG-B PWM and PPS signal formats. Enabling/disabling the output port and
selecting the signal format is controlled through the RUGGEDCOM ROS operating system.
The number of devices that can be connected to the TTL Out port is dependent on the cabling type and length,
as well as the input impedances of the devices. The following simplified circuit schematic shows the interface
between an IRIG-B source and connected devices.
V
S
R
S
R
C
R
L
/N
3
2
1
Figure 3: IRIG-B Simplified Circuit Schematic
1.
Source
2.
Cabling
3.
Device
The maximum number of devices (N) that can be connected to the source is determined by checking if the
source current (IS) required to drive the connected devices is less than the maximum drive current the source can
provide, and verifying that the load voltage (VL) the connected devices see is greater than the minimum required
voltage.
