Multichannel Systems Portable_ME-System Manual - Manual (Page 26)

Portable ME-System Manual
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Important: It is recommended to set the duration of a TTL pulse according to the sampling rate. The TTL
pulse must be long enough to cover at least one data point. For example, if you have a sampling rate of
10 kHz, a data point is recorded each 100 μs. Therefore, TTL input pulses must be at least 100 μs long to
make sure that it is detected by the system. MC_Rack will miss some or all pulses if the pulse duration is
shorter.
Please mask unused (not connected) digital input channels in the MC_Rack program to ignore undefined
states of the open inputs that can cause unwanted trigger events. Please see the MC_Rack manual for
more details.
Custom Switch for "Remote-Controlling"
You can connect any device that produces TTL outputs, for example a switch, to one of the digital input
bits. This means you can use a trigger for remote controlling the recording with MC_Rack, or for
synchronizing systems, if the data acquisition computer is not within reach during an experiment.
You can define the time length of the cutouts that are recorded around the trigger event in MC_Rack.
Please note that it is not possible to start the recording of a continuous data file with MC_Rack on a trigger,
but you can start a new data file on the trigger event. Please select the Recorder option "Create New File
On Trigger".
The picture shows a suggested circuit diagram for a switch used for remote controlling. The resistor and
capacitor work as a low-pass filter on the TTL signal and are necessary to reduce ringing of the signal.
Triggering other Instruments
The digital output of the Portable ME-System sends 20 ms TTL pulses (0 V = LOW and 5 V = HIGH).
This feature can be used to apply a feedback triggered by a signal or a parameter stream.
For example, you can connect the Trigger IN of an STG (stimulus generator) to the digital output. You
can also use the digital output for a synchronization of the Portable ME-System with other systems, for
example, for video tracking (provided that the other system of choice is able to receive TTL pulses). Please
see the documentation on the Digital Output instrument in the MC_Rack help or manual for more details.