DS5 Isolated Bipolar Constant Current Stimulator DS5 Operator's Manual 5.0
Enabling and Disabling the Audible “Information” Alerts
The DS5 will provide an “information” beep in response to all button
presses and switch actions by default. It is possible for the operator to
disable the “information” beep if they wish. F3 and F4 scroll through the
parameter choices. F1 accepts the hi-lighted setting and exits to the main
options screen.
Enabling and Disabling the Output Limits
By default, four limited parameters are monitored by the DS5 and if the
stimulus output exceeds any of these limits, the output is disabled and the
warning LED illuminates. This screen allows the operator to remove some
or all of these limits. F3 and F4 scroll through the parameter choices and
F2 removes (un-ticked) or re-instates (ticked) the limit. F1 confirms the
choices and returns to the main options menu. Refer to the Output Limits
section below for further information.
Maintenance Options
The maintenance screen gives the operator the opportunity to access four
further screens:-
Last Reset Cause - Displays the cause of the last reset.
Factory Defaults - Restores factory defaults to all options menu settings.
Diagnostics - Provides a scrollable list of internal memory which can be
used by Digitimer engineers for test purposes.
Exception Tests – Used by Digitimer Engineers for test purposes.
About - Details the hardware and firmware versions.
F3 and F4 scroll through the parameter choices, F1 selects the screen to
view while F2 exits to the main options menu.
Output Limits
Patient safety is of paramount importance when designing an electrical stimulator for clinical use. As a
result the DS5 incorporates several layers of safety features, many of which will never be apparent to the
operator. Amongst these are four output limits which control stimulus pulse energy, current and pulse
duration. However, in order to allow for a degree of clinical freedom, some output limits can be deactivated
by the operator. It should be noted that when these limits are deactivated, they generally do not remove
the limits, they merely shift them to more flexible values, without compromising patient safety.
By default the DS5 is factory configured with four output limits enabled. Through use of the Operator
Interface, these four limits can be toggled on and off. The Table 3.2 gives the values for these limits and
those that are implemented when they are disabled.
Limits and the Definition of a Pulse
For the purposes of defining stimulation waveforms, the operator should note that the DS5 will identify a
stimulus pulse as having been initiated when a current of over ±400µA is detected at the output,
whereupon, the DS5 will stop monitoring the baseline current (AvL, Average Low Level Current) and start to
monitor the parameters relating to a stimulation pulse (AvH, Average Pulse Current; PD, Pulse Duration and
PE, Pulse Energy), disabling the output if any of these exceed the pre-set limits. If the amplitude drops
below ±400µA then the DS5 reverts to monitoring AvL. If the polarity of the pulse was to change
instantaneously then the DS5 would interpret this as the termination of a pulse and the initiation of another.
Digitimer Ltd. 28 of 52 Copyright © 2009
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