White Rabbit provides sub-nanosecond accuracy and picoseconds precision of synchronization for large distributed systems. It also allows for deterministic and reliable data delivery. The device allows you to precision time-tag measured data and lets you trigger data taking in large installations while at the same time using the same network to transmit data.
These links provide additional information on White Rabbit devices and calibration procedures:
The White Rabbit switch (or wrs) is a major component of the WR network. Like any modern managed switch, the wrs includes a CPU with its own operating system. For more general information on the WR switch, see https://ohwr.org/projects/white-rabbit/wiki/switch or https://sevensols.com/wr-switch/.
The switch at HCRO is connected to a rubidium clock for precise timing and can currently be accessed from the nrdz-node1 server through ssh with the following command:
Or:
ssh [[email protected]](<mailto:[email protected]>)
There is no password currently so just press enter and you should now be connected to the switch. The switch in this case should be in grandmaster mode which means it will not show any synchronization information, but the slaves which will be discussed in the next section will let the user know whether the WR devices are synchronized.
To show the status of the WR switch, use the command wr_mon. The PTP state column should be set to master at all of the connected ports, and the MAC addresses should show in the appropriate column. As mentioned before, the synchronization status field should not show “Master mode or sync info not valid".
At this point, the switch is set up correctly, and an example of the output from the wr_mon command can be seen in the figure below.
Example wr_mon output
A node is connected to each sensor to synchronize data acquisition and processing across the entire array. Unfortunately, the software developed for these nodes is no longer being updated by the developers. This Github repository was used to connect to the WR-LENs from nrdz-node1 with scripts written in Python 2.
In order to run these scripts, the serial module needs to be installed, which in turn requires a pip associated with python 2 (pip2) to be installed first. Then, the install script at the top level of the repository is run in order to install all of the necessary libraries required for the scripts to run.
At this point, the shell.py script also at the top level of the py7slib repository is run with the IP address of the corresponding WR-LEN with the command PYTHONPATH=.. python2 shell.py <IP address>. On the note of IP addresses, the IP addresses of the 4 WR-LENs and their associated sensor are:
10.1.42.100 - Gate
10.1.42.101 - North
10.1.42.102 - West
10.1.42.103 - Chime
Now, the user is connected to the WR-LENs through a VUART shell, and when the command,
gui is entered, the following is displayed: