Digitimer Ltd – D188 Operator’s Manual
Version 1.2
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digital ring electrodes. The operator has the option of connecting as many pairs of electrodes as needed,
up to a maximum of eight.
If the electrode lead wires are too short, we offer pairs of output extension cables to increase the
distance between the D188 front panel and the subject. These are available in 1m long (D188-13) or 2m
long (D188-14) pairs.
Using Multiple D188’s with a Single Stimulus Source
In order to use more than one D188 and a single stimulator, it will be necessary for the user to connect
the stimulus source, in parallel, to the COM inputs of each D188. In this case, our D185-HB1 output
adaptor cable would be a suitable alternative to our D185-HB4. Alternatively, the stimulus source can be
connected to a single D188 and one output channel of that unit used to pass the stimulus to a second
D188. In this way, multiple D188’s can be “daisy chained” to one stimulator.
Using Manual Control
Manual control allows the operator to switch channels under mouse or keyboard control and is the best
method of control when specifically timed digital control is not required. We recommend that there is a
period of familiarisation, using the D188 in manual mode before any digital control protocols are
commenced. This allows the operator to test and optimize the physical connections between stimulus
source, computer, the D188 and the subject whilst also ensuring that the stimulator settings and
electrodes are appropriate for the chosen application.
Using External Digital Control
Due to the nature of the device, digital control will require the D188 to be interfaced with other
hardware which Digitimer may not supply or support. We therefore urge all users to take care when
programming automated electrode switching processes and stimulus delivery protocols, to ensure that
unexpected stimulation patterns are not delivered. All switching control protocols should be thoroughly
tested before any electrical stimulation is undertaken.
1:1 Digital Control
If the operator wishes to control the D188 using digital commands from a data acquisition board or other
device, the D188 has the option to be controlled by 8 TTL compatible (5V) digital outputs in a 1:1 manner.
The D188 is supplied with a communication cable which connects to the rear of the D188 via the 15-way
“D” connector input. The other end has tinned wires that can be soldered to a specific type of connector,
wired into a break-out box or used with screw terminals on a data acquisition interface. In this operating
mode, if Pin 1 (D0) is held TTL high, Channel 1 is active, if Pin 2 (D1) is held TTL high, Channel 2 is active
etc.
If more than one pin is set to TTL high, all outputs will be disabled, to prevent stimulation through
multiple channels.