Master and Slave Relationship - SyncBac PRO

Timecode Systems products, including your SyncBac PRO unit, use a relationship to maintain highly accurate clock settings. It is important that you understand how the master-slave relationship works, as you will need to set each SyncBac PRO in your BLINK network to run in either master mode (GP Master TX) or slave mode (RF Slave).

Tip: If you use a Timecode Systems :pulse as the master, you can do much more than synchronise the clocks. With the free BLINK Hub app, you can remotely control and monitor your SyncBac PRO units and the HERO4™ cameras they are attached to (see Did you know that you can monitor and control your SyncBac PRO and HERO4™ remotely, via a tablet or desktop PC or Mac? All you need is a Timecode Systems :pulse in your BLINK network and the free BLINK Hub application. ).

In the following sections, we explain how the master-slave relationship works and provide answers to some commonly asked questions:

When you understand the master-slave relationship, you can set your SyncBac PRO units to run in RF Slave mode or GP Master TX mode (see SyncBac PRO has two different Timecode modes: RF Slave and GP Master TX. These modes define how your SyncBac PRO's clock is synchronised with other devices, and so it is important that you choose the appropriate setting.).

Clock Synchronisation - Master and Slaves

To synchronise the clocks of multiple Timecode Systems devices, you need to set up a BLINK network. A BLINK network is a group of devices that are all set to the same country/area and the same RF Channel.

In the BLINK network, you need to have one 'master' device (a Timecode Systems device set to run in Master TX mode). The master device has the clock settings that you want all of the devices to use. All of the other devices in the BLINK network should be set to run as 'slaves'.

When a slave device is on, it transmits a signal (via the set RF Channel). If there is a master device within range and using the same RF Channel, the master detects the slave. It then sends its clock settings to the slave. The slave sets its own clock to match the clock of the master.

The master and slave communicate with each other regularly to make sure that their clocks are synchronised.

Note: There should be no more than one master per BLINK network. For more details, see What if there are Multiple Masters in the Same BLINK Network?.

How Can I Tell if a Slave is Communicating with a Master?

You can tell when a slave is connected with a master by looking at its main screen display. An antennae icon flashes in the top-right corner when the slave and master are communicating. The number shown to the right of the antennae icon shows the signal strength (0-7 where 7 is the maximum signal strength).

Note: The LED flashes blue if your SyncBac PRO has lost its connection to its master.

What if a Slave Can't Find a Master?

If your SyncBac PRO cannot connect to a master device, it will use its own clock settings instead. The most likely reasons for a slave being unable to connect to a master are that the master is out of range or the devices in the BLINK network are all set to run as slaves (so there is no master). A SyncBac PRO slave that runs using its own clock is often described as 'free running'.

When a SyncBac PRO slave is 'free running', it will continue to try and find a master device. As soon as it finds a master device within range and on the same BLINK network, it will try to connect and synchronise with the master.



Let's say you want to film two riders in a mountain bike event. Both of the riders are wearing HERO4™ cameras that have SyncBac PROs attached. The first rider, Paul, has his SyncBac PROs set to run in GP Master TX mode and use RF Channel 4. The second rider, Susan, has her SyncBac PRO set to run in RF Slave mode and use RF Channel 4. At the start, Paul and Susan's SyncBac PROs are within range of each other and so they synchronise their clocks.

During the event, Paul has a puncture and has to stop to repair it. During this time, Susan continues ahead and goes out of range of Paul. At this point, Susan's SyncBac PRO loses communication with Paul's master SyncBac PRO, and so it carries on using the clock settings that it has in place.

Paul fixes his puncture and catches up with Susan. His master SyncBac PRO is back in range of Susan's slave SyncBac PRO and so they connect and re-synchronise.

What if there are Multiple Masters in the Same BLINK Network?

You should set up your Timecode devices so that there is one master device per BLINK network. This ensures that all of the slave devices synchronise with the same clock (the clock of the master device).

If you have multiple masters in the same BLINK network, each slave will connect to the first master that detects it. There is no guarantee that all of the slaves will connect to the same master, and so this can lead to differences in the clocks.


Let's say you have a BLINK network where all of the devices are set to use RF Channel 4. There is one master (:pulse), and three slaves (SyncBac PROs).

The devices in the network are all turned off and you add a new SyncBac PRO to the BLINK network. The new SyncBac PRO is set to run in GP Master TX mode, so when the devices are all turned back on, there are two masters in the BLINK network - the :pulse and the new SyncBac PRO.

The slave SyncBac PROs will attempt to connect to the first master they find. Two of the SyncBac PRO slaves connect to the :pulse master first, and so synchronise with that clock. The other SyncBac PRO connects with the new SyncBac PRO first and so synchronises with that clock. As a result, the devices in the BLINK network are not synchronised to the same clock.

For this reason, make sure that there is one master device per BLINK network.


Remote Control with :pulse and BLINK Hub

If you use a Timecode Systems :pulse as a master device, you can do much more than just synchronise the clocks. The :pulse and the free BLINK Hub app allow you to:

  • Control your SyncBac PRO slaves and the HERO4™s remotely
  • View the status of SyncBac PRO slaves in BLINK Hub
  • View the status of the HERO4™ cameras that are connected to your SyncBac PRO slaves.

To learn about monitoring and controlling your SyncBac PRO units remotely, please refer to the :pulse user guide.

Note: When :pulse masters communicate with slave devices, they can set the clocks, receive status information, and send controls. Remote monitoring and control is only available with :pulse. SyncBac PRO and :wave masters can only set the clocks of slave devices - they do not support remote controls.

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