Multichannel Systems MEA-System Manual - Manual (Page 20)

4 Troubleshooting
4.1 About Troubleshooting
The following hints are provided to solve special problems that have been reported by users.
Most problems occur seldom and only under specific circumstances. Please check the mentioned
possible causes carefully when you have any trouble with the product. In most cases, it is only
a minor problem that can be easily avoided or solved.
If the problem persists, please contact your local retailer. The highly qualified staff will be glad
to help you. Please inform your local retailer as well, if other problems that are not mentioned
in this documentation occur, even if you have solved the problem on your own. This helps other
users, and it helps MCS to optimize the instrument and the documentation.
Please pay attention to the safety and service information in the separate manuals of the related
products and in the software help. Multi Channel Systems has put all effort into making the
product fully stable and reliable, but like all high-performance products, it has to be handled
with care.
4.2 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 of the USB device or the interface board of the MEA2100-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:
? You have mismatched the digital input with the analog input. To test this, please add a Digital
Display to your virtual rack. You should see the trigger event as a logical state of HIGH (=1).
If you cannot see any signals, please add a Data Display to your rack and select the analog raw
data as the input stream. Make sure the channel layout map of the display shows all three / four
analog input channels (A1 to A4). If you have mismatched the inputs, you will now see the
(clipped) trigger events.

Connect the TTL source to the “Digital In” of the USB device or to the interface board of the
MEA2100-System. If you have only one instrument for triggering recording (for example, the
Sync Out of a stimulus generator), connect it to bit 0 or to D0 IN.

If you use a digital in / out extension (Di/o) accessory, you can connect up to 16 digital input
sources and up to 16 devices that you want to be triggered by the Digital Output instrument
of MC_Rack.
? The TTL source does not generate true TTL signals (5 V), or the TTL pulse is shorter than 200 μs.
 The USB device can only accept TTL signals (CMOS 5 V TTL level) as a digital input stream.
A minimum TTL pulse of 200 μs is recommended. Otherwise, a detection of the trigger by
the USB device is not 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 digital inputs 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.