Multichannel Systems MC_Rack Manual - Manual (Page 96)

MC_Rack Manual
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4.3 Data Streams and Channels
4.3.1 Data Stream Types
A data stream can include several channels of the same data type. The term channel means
the data from a single MC_Card input pin, that is, electrode.
Several different data streams can be generated, handled, processed, and recorded by MC_Rack.
Data streams are either acquired by the MC_Card or an USB based data acquisition device,
for example, Electrode Raw Data, Analog Raw Data, and Digital Data; or they are generated
by MC_Rack when processing input streams, for example, Trigger, Parameter, Spikes and Filtered
Data.
You can adjust the number of analog and electrode channels according to your hardware
in the Channel Layout dialog box, up to a total of 256 channels. One digital input stream
with 16 channels (input bits) is available.
If you assign data to MC_Rack instruments, for example, the Recorder, you can select complete
data stream(s), or you can pick individual channels of interest from a data stream.
In the following list, all data streams available in MC_Rack are briefly described. Some more
complex data stream types are explained in more detail in the following chapters.
Definition of Data Stream Types
Electrode
Raw Data: Unprocessed analog data acquired from an amplifier, for example, from
a MEA amplifier for MEA electrodes or from a ME preamplifier like MPA8I.
The amplifier gain can be specified in MC_Rack, so that the original signal
is calculated automatically.
Analog
Raw Data: Analog non-amplified data that is directly delivered to the MC_Card via
BNC connectors, for example, channels A1, A2, A3 in the typical MEA layout.
In USB-MEA- or USB-ME-Systems four additional analog channels are available.
The data are delivered to the internal data acquisition, and send to the data
acquisition computer via USB High Speed. You can use it to record additional
information from external devices, for example, the heart rate, and so on.
You can connect the Sync Out of a STG (stimulus generator) to an analog input
to synchronize stimulus application and recording.
Digital
Data: The 16 digital input channels of the MC_Card can be used to record additional
information from external devices as a 16-bit encoded number, or you can
connect the Sync Out of a STG (stimulus generator) to a single input bit for
synchronizing stimulation and recording. A digital IN /OUT connector is also
available in USB-MEA- and USB-ME-Systems. The 16 digital input channels are
represented as the Digital Data stream, that is, a stream of 16-bit values, each
bit (0 to 15) representing one digital input. Standard TTL signals are accepted as
input signals on the digital inputs. There are two possible logical states for each
bit: 0 (low = 0 V) and 1 (high = 5 V). The digital input channels are sampled
with the overall sampling rate selected in MC_Rack.
In the standard configuration, TTL signal sources can be connected to 3 BNC
inputs (input bits 0, 1, 2). Alternatively, a 68-pin socket supporting all 16 input
and output bits and a digital in / out extension with 16 BNC inputs and outputs
can be ordered as accessories. Unused input bits, which have an undefined
state, should be masked in the Trigger Detector.
For example, if the digital input bit 0 is set to high, the binary 16-bit value will
be 0000000000000001, or 1 as a decimal number. If channel 2 is set to high, the
value is (binary) 0000000000000010, or (decimal) 2, and so on. Any combination
of logical states of input bits is represented by the 16-bit value.
For more details on the use of the Digital Data stream for triggering MC_Rack,
please see the chapter Trigger Detector under MC_Rack Features. For more
background information on digital data and binary code, please see the