Elan Digital Systems Ltd. 3 USBcount50 USER’S GUIDE Iss1
Disclaimer
This document has been carefully prepared and checked. No responsibility can be
assumed for inaccuracies. Elan reserves the right to make changes without prior notice
to any products herein to improve functionality, reliability or other design aspects. Elan
does not assume any liability for loses arising out of the use of any product described
herein; neither does its use convey any license under its patent rights or the rights of
others. Elan does not guarantee the compatibility or fitness for purpose of any product
listed herein. Elan products are not authorized for use as components in life support
services or systems. Elan should be informed of any such intended use to determine
suitability of the products.
Software supplied with Elan PC-Cards, Compact Flash cards or USB devices is
provided “as-is” with no warranty, express or implied, as to its quality or fitness for a
particular purpose. Elan assumes no liability for any direct or indirect losses arising
from use of the supplied code.
This equipment has been tested and found to comply with the limits for a Class A digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses, and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:
- Reorient or relocate the receiving antenna
- Increase the separation between the equipment and receiver
- Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
- Consult an Elan authorized dealer or service representative for help.
Elan is not responsible for any radio or television interference caused by using other than
recommended cables and connectors or by unauthorized changes or modifications to this equipment.
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 USBcount50 USER’S GUIDE Iss1
1 OVERVIEW
The USBcount50 is an isolated digital pulse counter that has the
following features:
• Single channel pulse counter with BNC input and USB PC
interface
• Each USBcount50 can be stacked to increase channel count (each
requires its own USB connection)1
• 300V Cat II isolation between BNC ground and USB ground
2
This means that there is no DC path through the USBcount50
from the counters input to the PC’s ground
• Up to 50MHz input counting, 100MHz with suitable input signal
• 10ns timing resolution
• Single shot or continuous update
• 28-bit counter gives 268 million : 1 dynamic range
• Two modes of operation: Frequency mode or Period mode
• Frequency mode can use 0.1s, 1s or 10s integration times. Large
dynamic range of counter means 1s integration setting can be
used from 1KHz up to 100MHz i.e. no auto-ranging required
• Period mode can use internal 1MHz, 10MHz or 100MHz
reference clocks coupled with edge detection logic for
rising→rising, falling→falling, falling→rising, rising→falling.
Large dynamic range of counter means 100MHz clock setting can
be used from 10us up to 26.8s i.e. no auto-ranging required
• Period mode (aka reciprocal counting mode) is able to measure
frequencies down to below 4mHz.
• Programmable input stage voltage level from 1.5V to 5.0V in 256
steps
• Input protected to 30V DC
• Host powered from USB (200mA typ)
• Stacked configurations of 2,3 and 4 channels are supported
• Power/activity LED
1
A stacking connector kit is required
2
In stacked configurations the channels share a common ground at the BNC terminals
Elan Digital Systems Ltd. 5 USBcount50 USER’S GUIDE Iss1
2 ABOUT THE USBcount50
2.1 General
The USBcount50 has been designed to allow a broad range of input
frequencies and pulses to be measured. The input stage supply is
programmable to allow the counter to work in circuits generating
various Voh levels.
Each USBcount50 can be used as an independent single channel
counter but to enhance flexibility several USBcount50s can be
stacked together to make a combined 2,3 or 4-channel device. In
this case, each counter is synchronised with the others so that the
compound device acts like a single multi-channel instrument. Each
USBcount50 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.
Elan Digital Systems Ltd. 6 USBcount50 USER’S GUIDE Iss1
2.2 USBcount50 Architecture
The figure below shows a simplified diagram of the USBcount50.
STACK
INPUT PROTECTION
BNC
`
Vsupply
CONTROLLER
&
COUNTER
8-BIT DAC
CONN
DATA
PSU
USB
CONTROLLER
USB
ISOLATION BARRIER
Figure 2.2-1 USBcount50 Architecture Diagram
Elan Digital Systems Ltd. 7 USBcount50 USER’S GUIDE Iss1
2.3 Using More Than One USBcount50
2.3.1 Stacked Mode
A unique feature of the USBcount50 architecture is that up to 4
devices3 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:
2.3.1.1 Assembling The Stack
To stack the USBcount50 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
counters (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 counter.
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 counter’s internal connector. You should
be able to see the gold pins about 2-3mm beyond the bottom surface
of the counter. The connectors have no pin orientation…they can go
in 2 possible ways round…both are OK.
3
Don’t stack more than 4, the software will reject this.
Elan Digital Systems Ltd. 8 USBcount50 USER’S GUIDE Iss1
Repeat this for all except the last counter to be stacked.
For the last counter 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 counter’s case. This counter MUST be the bottom counter 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 counter is connected to a high voltage and
you could get an electric shock! Similarly, if you plan to use only
one counter, 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 USBcount50 USER’S GUIDE Iss1
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