Integrators Guide - Light 97
© 2018 Nortek AS
Generate the start on sync trigger from the other instrumentation.
4.3.2 Vectrino
The Vectrino can serve as master for other Vectrinos, or its sampling can be controlled by other
sensors. If one connects a controller to the Vectrino, a fairly sophisticated system in which the
controller can power the Vectrino and provide it with sync pulses to control the sampling accurately
can be set up. The controller can serve as a storage device.
Note: A Vectrino can operate as a master for a Vector, but the opposite is not possible.
The Vectrino can be synchronized with other instruments via a pair of sync lines. To avoid noise
problems and to make cabling easier, the two sync lines are RS485 which is balanced and bi-
directional. The sync lines are labeled Sync– and Sync+. Some instruments have incorrect labels
on the sync lines, if the labels read Sync in and Sync out they should be treated as Sync- (Sync In)
and Sync+ (Sync Out). The polarity is not too important as the sync scheme is quite insensitive to
the polarity.
Firmware version V1.30 Plus supports synchronisation of transmit pulses to avoid both electric and
acoustic interference when operating several Vectrinos together. This feature is only available in the
Plus version.
How Synchronization Works
Output Sync (Vectrino operating as the master) transmits a pulse on RS485 with a duration of 40 µs.
Sync+ for Vectrino transmits the pulse by the end of the sampling interval and a single pulse at the
beginning of the first sampling interval to start everything. For other sensors, Sync+ transmits a
pulse at the middle of the sampling interval. Input Sync triggers on any edge, rising or falling, on
RS485. After each trig, the input is discarded for the next 64 µs.
RS485 levels
These levels define the signal the Vectrino reads for Input Sync:
High level: Sync+ > Sync– by 200 mV
Low level: Sync+ < Sync– by 200 mV
Synchronizing Multiple Vectrinos
Connect all the Sync+ lines together and all the Sync– lines together. All instruments should
share a common ground.
Select one instrument as the master and the rest as slaves (Input sync) in the software.
Start data collection in all slaves before starting the master. The slaves will then wait for the first
sync pulse from the master before sampling commences.
If you use Sample on sync, all instruments should be configured with the same sampling rate.
We have checked that there is no interference between Vectrinos once they are properly
synchronized but have not tested how close they can be during operation. An intelligent guess is
that they should be at least 5-10 cm apart to avoid acoustic interference.
Example: Synchronizing From a TTL Source
TTL signal levels can be mixed with the RS485 levels of the Vectrino:
Connect your sync pulse to Sync+ and connect Sync– to a constant voltage, 1.5 volts for
instance. This provides a defined transition when the TTL signal changes, which is not the case if
you ground Sync–.
When Vectrino functions as master, the Sync+ line can be connected to the TTL input and the two
systems must be connected so they share common ground.
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