Elan Digital Systems Ltd. 3 USBscope50 USER’S GUIDE Iss5
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Unauthorized changes or modifications could void the user's authority to operate the equipment.
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions (1) this device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
Listed Products
The models covered by this installation guide are intended only for installation in Listed computers for
use in business or home.
Elan Digital Systems Ltd. 4 USBscope50 USER’S GUIDE Iss5
1 OVERVIEW
The USBscope50 is a digital storage oscilloscope that has the
following features:
• Single channel scope with BNC input and USB PC interface
• Each USBscope50 can be stacked to increase channel count (each
requires its own USB connection)1
• 300V Cat II isolation between BNC ground and USB ground2
• 50MSample/sec single shot sample rate
• 1GSample/sec equivalent sample rate
3
• Timebase from 4ns/div to 4s/div in 1,2,4 steps
• 75MHz 3dB analogue bandwidth4
• 3000 sample points, 8-bits per sample
• Pre and post triggering, and trigger delay
5
• AC and DC coupling
• Input sensitivities with x1 probe are 30mV/div, 300mV/div,
3V/div and with x10 probe are 300mV/div, 3V/div, 30V/div
• 1Meg input impedance, 16pF
• Channel offset control
• Auto and Normal hardware triggering with >, <, +, – modes
• Host powered from USB (200mA typ)
• Stacked configurations of 2,3 and 4 channels are supported
• Stacked configurations allow any channel to be trigger channel
• Stacked configurations have tight phase locking between channels
• Probe compensation output, 3V 1KHz
• Power/activity LED
1
A stacking connector kit is required
2
In stacked configurations the channels share a common ground at the BNC terminals
3
Suitable to measure repetitive signals that are not phase locked with the internal acquisition clock
4
Hardware trigger bandwidth is approximately 60MHz
5
Only in single-shot mode
Elan Digital Systems Ltd. 5 USBscope50 USER’S GUIDE Iss5
2 ABOUT THE USBscope50
2.1 General
The USBscope50 uses a 50MSample/sec 8-bit A-to-D converter.
The A-to-D and front-end circuits that process the input waveform,
and the digital stages that acquire and store the waveform are all
powered from the USB host interface via an isolated supply. This
means that there is no galvanic connection between the BNC ground
(or BNC centre terminal), and the USB interface. When you
measure a circuit and connect the scope ground clip to a voltage that
is not at the same ground potential as the host computer, no current
can flow and the host computer is therefore not forced to be at the
same potential as the circuit under test. This clearly has major safety
advantages. The USBscope50 has been designed so that up to 300V
6
CAT II
, or 500V CAT I can exist between the scope ground clip
and the host computer ground.
Each USBscope50 can be used as an independent single channel
scope but to enhance flexibility several USBscope50s can be stacked
together to make a combined 2,3 or 4-channel device. In this case,
each scope is synchronised with the others so that the compound
device acts like a single multi-channel instrument. Each
USBscope50 still needs its own USB connection and the combined
device shares a common ground between all the BNC connectors i.e.
the channels are isolated from the USB but not from each other.
6
The CAT rating refers to how large a transient over-voltage may be when connected to the circuit in
question. The USBscope50 is designed to handle a certain transient over-voltage between the BNC
and the USB host i.e. across the internal isolation circuits. The CAT II UL rating defines a more
severe environment than CAT I and hence larger transients are possible. This is why the isolation
rating for CAT II is lower than the rating for CAT I. For further information on CAT ratings please
refer to www.fluke.com
Elan Digital Systems Ltd. 6 USBscope50 USER’S GUIDE Iss5
2.2 USBscope50 Architecture
The figure below shows a simplified diagram of the USBscope50.
STACK
CONN
DATA
PSU
ISOLATION BARRIER
USB
CONTROLLER
USB
BNC
AC/DC
ATTENUATOR
1Meg
AMP
COMP
CONTROLLER
Trigg er
8-BI T ADC
Figure 2.2-1 USBscope50 Architecture Diagram
Elan Digital Systems Ltd. 7 USBscope50 USER’S GUIDE Iss5
2.3 Using More Than One USBscope50
A unique feature of the USBscope50 architecture is that up to 4
devices7 can be stacked to make a multi-channel instrument.
In order to use a stacked configuration, you must purchase the stacking connector kit. This kit comprises 3 long lead connectors
and 1 short lead connector as shown:
2.3.1 Assembling The Stack
To stack the USBscope50 devices, first be sure that none of them are
connected to a USB port.
Before you begin, put the short lead connector to one-side…you’ll
use that one last.
Now, insert one of the long connectors from the top of one of the
scopes (it doesn’t really matter which one). Push the pins of the
connector into the top of the stacking connector from the side where
you can see the top of the black connector down inside the scope.
Be careful when doing this, don’t use too much force or you may
damage the connector pins. Push the long connector all the way in
until it seats down on the scope’s internal connector. You should be
able to see the gold pins about 2-3mm beyond the bottom surface of
the scope. The connectors have no pin orientation…they can go in 2
possible ways round…both are OK.
7
Don’t stack more than 4, the software will reject this.
Elan Digital Systems Ltd. 8 USBscope50 USER’S GUIDE Iss5
Repeat this for all except the last scope to be stacked.
For the last scope in the stack, do the same as above but use the short
length connector. This time, the pins are shorter so they stop well
inside the scope’s case. This scope MUST be the bottom scope in the stack. The reason for this is that if you use the long connector,
the pins could be shorted out accidentally, or you may touch the pins
when the scope is connected to a high voltage and you could get an
electric shock! Similarly, if you plan to use only one scope, make
sure there is no stack connector fitted or the shorter connector type is
fitted.
This is a safety critical point so please note it carefully.
Now you can assemble the stack.
Elan Digital Systems Ltd. 9 USBscope50 USER’S GUIDE Iss5
Start with the bottom scope. Hold it in one hand, and put the next
scope on top of the 1st, the same way around. Align the stacking
connectors and when the stacking connectors are partly mated
engage the front “P” shaped clip (BNC end) on the 2nd scope into the
“P” shaped slot on the 1st scope.
nd
Now, bring the back edge “P” clip (USB end) of the 2
scope down
until it clicks into the 1st scope’s slot. These two scopes are now
mated.
Check that as you pushed the 2nd scope down, the stack connector
has not been forced upward…if it has simply press it down until it
seats correctly (see picture above for a guide as to the normal
exposed connector depth after stacking). Repeat this for each
remaining scope, adding each one on top of the previous one.
The scopes are now stacked.
2.3.2 Disassembling The Stack
Start with the top scope in the stack. Grasp the stack in one hand
and with the other hand’s thumb and forefinger, pinch between the
interface between the top two scopes, near the back “P” clip (USB
end). With moderate force, the top scope will pop up and come free.
Remove the stacking connector from the free scope.
Repeat this for all scopes in the stack.
Elan Digital Systems Ltd. 10 USBscope50 USER’S GUIDE Iss5
2.3.3 USB Connections For Stacked Configurations
All stacked scopes need a USB connection. A standard hub may
be useful for multi-channel stacks to get enough USB ports.
Each scope needs about 200mA. Plugging more than 2 scopes into a
hub will mean that the hub may need to be powered externally.
Please refer to the hub’s documentation for more details about the
power available per port.
2.3.4 Software For Stacked Configurations
When you run USBscope50, it will automatically detect the scopes
connected via USB and will also check to see if the scopes are
electrically connected together via the stack. It will then initialise all
connected scopes, one at a time. This may take a few seconds.
If you stack several scopes but forget to connect say one of the
scopes to a USB port, the software will warn you and will not run.
The software will display a channel “tab” for each scope in use.
The channel number allocated to each scope depends on its serial
number, so the order you stacked them will almost certainly NOT be
the same as the channel order allocated by software.
To find out which scope is Channel 1, use the CH1 tab and click the
“id” button.
The LED on that scope will blink rapidly for about 4 seconds, or
until you click the button again.
Elan Digital Systems Ltd. 11 USBscope50 USER’S GUIDE Iss5
Repeat this for each channel in the stack to identify them.
If you like, you can stop the software, and unplug all the scopes from
their USB connections, and then re-stack them in their channel order.
The “about” tab lists all the scopes that have been found. Click on
any of the scopes in the list to see more information and an
explanation of items in the list.
Elan Digital Systems Ltd. 12 USBscope50 USER’S GUIDE Iss5
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