Multichannel Systems STG4002 Manual - Manual (Page 59)

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10
Synchronizing Events
10.1 Digital Output Signals (Sync Out)
The output of the digital Sync Out outputs is a 3.3 V TTL signal. A logic state of 1 means 3.3 V,
and a logic state of 0 means 0 V. Please note that the digital output is about 15 μs faster than
the analog output. This small offset is generally sufficient to make sure that the Sync Out signal
precedes the stimulation, which is important for synchronizing events.
You can program the output signal of the Sync Out channels in the same way as the analog
output signals, but due to the nature of a digital signal, only values of 0 and 1 are allowed.
A Sync Out signal is generated each time when the STG is started.
The output signal can be used for triggering external devices, for example, the data acquisition
with the MC_Card of the ME-System and the MEA-System. Please note that if you use it for
triggering the MC_Card, you should use output signals that have a duration of at least 200 μs.
Otherwise, it can happen that the MC_Card ignores trigger events.
All available Sync Out outputs are active when the STG is started by pressing the Start / Stop
button, or by using the software command Start on the STG menu.
If you are using the Trigger In inputs for starting the STG, each of the Sync Out channels is
controlled by a separate Trigger In channel. Sync Out 1 is active when Trigger In 1 is triggered,
Sync Out 2 is active when Trigger In 2 is active. The assignment of Sync Out channels to Trigger
In inputs can be customized, please see chapter “Trigger Settings”.
If you use the Repeat feature in the Trigger Settings dialog box, the corresponding Sync Out
signal is repeated as well as the selected analog output signals.
You can, for example, synchronize separate displays or other virtual instruments in MC_Rack,
one for each trigger input. You can also define a bit pattern in the Trigger Detector and trigger
instruments on this bit pattern, for example to activate virtual instruments only when trigger 1
and 2 are active at the same time. Please see the MC_Rack help or manual for more information
on the Trigger Detector and triggering.
Note: No Sync Out signal is sent when the STG is stopped on a trigger event or by pressing
the Start / Stop button, that is, if the trigger event occurs or the button is pressed when
the STG has still been active.
Timing of blanking signal
If you have a MEA amplifier with blanking circuit in use, you can apply a blanking signal
(TTL pulse) for transiently switching off the input stage of the amplifiers during the stimulus,
thus avoiding the stimulus artifact.
MCS recommends a minimum blanking pulse that starts with the stimulus and stops 100 μs
after the stimulus. The fact that the digital output of the stimulus generator from MCS is about
15 μs faster than the analog output ensures that the blanking signal is delivered before the
stimulus. It is very important that the blanking pulse is delivered shortly before the stimulus.