Multichannel Systems USB-MEA256-System Manual - Manual (Page 30)

USB-MEA256-System Manual
24
5.3 Triggering / Digital Input does not Work
You have connected a TTL source (for example, the Sync Out of a stimulus generator) to the
digital input D0 of the USB-MEA256-System, and configured the virtual rack in MC_Rack
for triggering displays or data acquisition by the TTL source, but you do not see any sweeps.
Possible causes:
? The TTL source does not generate true TTL signals (5 V TTL level), or the TTL pulse duration
is too short in combination with the sampling rate, so that the pulse is missed in-between two
data points.
The USB-MEA256-System can only accept TTL signals (5 V TTL level) as a digital input stream.
The TTL pulse needs to be optimized according to the sampling rate. Otherwise, a detection
of the trigger cannot be guaranteed.
? The software settings for the Trigger Detector do not match with the hardware configuration.
In MC_Rack, add a Trigger Detector to your virtual rack, and select the Digital Data D1 input
stream as the Trigger. Check the pin layout of the Digital IN/OUT connector and make sure that
the same bit input that is connected is selected in the software. (The standard settings of the
Trigger Detector are for using bit 0.) Mask all unused bits. Select the appropriate logical state
(generally HIGH) for triggering. Please see the MC_Rack help or manual for more details.
5.4 Noise on Single Electrodes
The noise level on single electrodes is significantly higher than expected or you see artifact signals.
Possible causes:
? The electrode or the contact pin of the amplifier may be defective. To test this, do the following.
Open the amplifier and turn the 256MEA by 90 degrees. Close the amplifier again and start
the recording.
If the same electrode in the MEA layout is affected, the amplifier's contact is not okay.
If another electrode is now affected and the previously affected electrode is okay now,
the 256MEA electrode is not okay, but the amplifier is fine.
— OR —
Use the test model probe to test the amplifier. If the noise level is fine without the MEA,
bad MEA electrodes cannot be the cause.