Measurement Computing Switch & Sense 8/8 User manual

Switch & Sense 8/8
USB-based Isolated Input and Relay Output
User's Guide
May 2021. Rev 8
© Measurement Computing Corporation

2
Switch-Sense-8-8.docx
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Notice
Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for
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into the body, or b) support or sustain life and whose failure to perform can be reasonably expected to result in
injury. Measurement Computing Corporation products are not designed with the components required, and are
not subject to the testing required to ensure a level of reliability suitable for the treatment and diagnosis of
people.

3
Table of Contents
Preface
About this User's Guide ..................................................................................................................... 4
What you will learn from this user's guide ..................................................................................................... 4
Conventions in this user's guide..................................................................................................................... 4
Where to find more information..................................................................................................................... 4
Chapter 1
Introducing the Switch & Sense 8/8 .................................................................................................. 5
Overview: Switch & Sense 8/8 features ......................................................................................................... 5
Functional block diagram .............................................................................................................................. 6
Chapter 2
Installing the Switch & Sense 8/8 ...................................................................................................... 7
Unpacking ..................................................................................................................................................... 7
Installing the software.................................................................................................................................... 7
Connecting the external power supply ........................................................................................................... 7
Installing the hardware .................................................................................................................................. 7
Chapter 3
Functional Details ............................................................................................................................... 8
External components ..................................................................................................................................... 8
Direct current (dc) power connector and +9 V power supply ...............................................................................................8
External power LED................................................................................................................................................................9
Status LED...............................................................................................................................................................................9
USB connector.........................................................................................................................................................................9
Internal components ...................................................................................................................................... 9
Screw terminals and relays .....................................................................................................................................................9
Main connector and pinout .......................................................................................................................... 10
Relay contact terminals (NO, C, NC (0) to NO, C, NC (7))................................................................................................11
Differential isolated digital input terminals (IP0A to IP7B)................................................................................................12
Chapter 4
Specifications.................................................................................................................................... 15
USB compliance.......................................................................................................................................... 15
Power consumption ..................................................................................................................................... 15
Output specification..................................................................................................................................... 15
Isolated inputs ............................................................................................................................................. 15
USB connection........................................................................................................................................... 16
Environmental ............................................................................................................................................. 16
Mechanical .................................................................................................................................................. 16
Screw terminal............................................................................................................................................. 16
Miscellaneous.............................................................................................................................................. 16
Screw terminal pinouts ................................................................................................................................ 16

4
Preface
About this User's Guide
What you will learn from this user's guide
This user's guide describes the Measurement Computing Switch & Sense 8/8 data acquisition device and lists
device specifications.
Conventions in this user's guide
For more information
Text presented in a box signifies additional information related to the subject matter.
Caution! Shaded caution statements present information to help you avoid injuring yourself and others,
damaging your hardware, or losing your data.
bold text Bold text is used for the names of objects on a screen, such as buttons, text boxes, and check boxes.
italic text Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase.
Where to find more information
Additional information about Switch & Sense 8/8 hardware is available on our website at www.mccdaq.com.
You can also contact Measurement Computing Corporation with specific questions.
Knowledgebase: kb.mccdaq.com
Tech support form: www.mccdaq.com/support/support_form.aspx
Email: [email protected]
Phone: [phone] and follow the instructions for reaching Tech Support
For international customers, contact your local distributor. Refer to the International Distributors section on our
website at www.mccdaq.com/International.

5
Chapter 1
Introducing the Switch & Sense 8/8
Overview: Switch & Sense 8/8 features
This user's guide contains all of the information you need to install, configure, and program the Switch & Sense
8/8.
The Switch & Sense 8/8 is a USB 1.1 low-speed device used for data acquisition and control. It is designed for
USB 1.1 ports, and was tested for full compatibility with both USB 1.1 and USB 2.0 ports. The Switch & Sense
8/8 is supported under popular Microsoft®Windows®operating systems.
The Switch & Sense 8/8 offers eight single pole double throw (SPDT) Form C relays and eight isolated inputs.
You can configure each of the isolated inputs with an optional input filter. The input filters are enabled and
disabled by software control.
The Switch & Sense 8/8 is shown here. All I/O connections are made to four sets of screw terminals.

Switch & Sense 8/8 User's Guide Introducing the Switch & Sense 8/8
6
Functional block diagram
Switch & Sense 8/8 functions are illustrated in the block diagram shown here.
Figure 1. Switch & Sense 8/8 functional block diagram
USB
Controller
Control
Registers
Control
Bus
FORM C
Relay Outputs
Control
Relays 0 to 7
Differential Isolated Inputs
Control
9 VDC external
power supply
9V
D+ D- Vcc Gnd
USB
HOST
Universal Serial Bus (1.5 MBS)

7
Chapter 2
Installing the Switch & Sense 8/8
Unpacking
As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the board from its packaging, ground yourself using a wrist strap or by simply
touching the computer chassis or other grounded object to eliminate any stored static charge.
Installing the software
Refer to the Switch & Sense 8/8 product page on our website for information about the software supported by
the Switch & Sense 8/8.
Install the software before you install the hardware
The driver needed to run the device is installed when you install the software. Therefore, you need to install the
software package you plan to use before you install the hardware.
Connecting the external power supply
Power to the Switch & Sense 8/8 is provided with the 9 V, 15 W external power supply (CB-PWR-9). To
connect the power supply to your Switch & Sense 8/8, do the following:
1. Connect the external power cord to the power connector labeled 7.5-20Vdc on the back of the Switch &
Sense 8/8.
2. Plug the AC adapter into a power outlet.
The EXTERNAL POWER LED illuminates green when 9 V power is supplied to the Switch & Sense 8/8. If the
voltage supply is less than 7.5 V or more than 20 V, the LED does not light.
Installing the hardware
Install the software before you install your device
A driver needed to run the Switch&Sense 8/8 is installed when you install the software. Therefore, you need to
install the software package you plan to use before you install the hardware.
We recommend that you run Windows Update to update your operating system with the latest USB drivers.
To connect the Switch & Sense 8/8 to your system, turn on your computer and connect the USB cable to an
available USB port on the computer or to an external USB hub connected to the computer. Connect the other
end of the USB cable to the USB connector on the device. No external power is required.
When you connect the device for the first time to a computer running Windows, a Found New Hardware dialog
opens when the operating system detects the device. The dialog closes after the device is installed.
A green Status LED indicates the device status. When the LED is on, the device is powered and ready for
operation. When the LED is off, the device is not powered or did not initialize.
Contact technical support if your system does not detect the Switch & Sense 8/8.

8
Chapter 3
Functional Details
The Switch & Sense 8/8 expands the capabilities of desktop personal computers by providing SPDT relay
control and isolated inputs in a plug-and-play package. Screw terminals provide easy field wiring to the three
output lines for each of the eight on-board relays.
In addition, two terminals are provided for the differential input signals associated with each of the eight
isolated inputs.
External components
The Switch & Sense 8/8 has the following external components, as shown below.
Direct current (dc) power connector
External power LED
Status LED
USB connector /cable
Figure 2. Switch & Sense 8/8 external components (rear view)
Direct current (dc) power connector and +9 V power supply
The Switch & Sense 8/8 requires between +7.5 V and +20 V of external power. Your computer can configure
the Switch & Sense 8/8 without external power. However, external power connection is required to activate the
relays and to run tests in InstaCal.
The USB specification allows high power devices to draw up to 500 mA. When all eight relays are energized,
the collective current draw exceeds the maximum allowed for high power USB devices. Therefore, external
power is required.
Use the +9-volt (V) DC power supply cord shipped with the Switch & Sense 8/8 to provide external power to
this connector.
STATUS
LED
EXTERNAL POWER
LED
USB connector/cable
Direct Current
power connection
(7.5 to 20 V)

Switch & Sense 8/8 User's Guide Functional Details
9
External power LED
The LED labeled EXTERNAL POWER lights up when the Switch & Sense 8/8 is connected to an external
power source. It uses up to 5 mA of current and cannot be disabled.
Status LED
The LED labeled STATUS indicates the communication status of the Switch & Sense 8/8. It uses up to 5 mA of
current and cannot be disabled.
Status LED illumination
LED Illumination Indication
Steady green
The Switch & Sense 8/8 is connected to a computer or external USB hub.
Blinks continuously
Data is being transferred.
Blinks three times
Initial communication is established between the Switch & Sense 8/8 and the computer.
USB connector
The USB connector on the back of the Switch & Sense 8/8 enclosure provides +5 V power and communication.
Internal components
Screw terminals and relays
The Switch & Sense 8/8 has four rows of screw terminals — two outer rows containing 12 terminals each, and
two inner rows containing eight terminals each.
The outer rows of terminals connect to the eight relays available from the Switch & Sense 8/8.
The inner rows connect to the differential isolated digital inputs. No additional components are required to
terminate any of the input or output signals.

Switch & Sense 8/8 User's Guide Functional Details
10
Figure 3. Switch & Sense 8/8 screw terminals and relays
Main connector and pinout
Connector specifications
Connector type
Screw terminal
Wire gauge range
12 AWG to 20 AWG
Screw terminal pin out
Pin
Signal Name
Pin
Signal Name
IP0A
Input 0 terminal A
IP4A
Input 4 terminal A
IP0B
Input 0 terminal B
IP4B
Input 4 terminal B
IP1A
Input 1 terminal A
IP5A
Input 5 terminal A
IP1B
Input 1 terminal B
IP5B
Input 5 terminal B
IP2A
Input 2 terminal A
IP6A
Input 6 terminal A
IP2B
Input 2 terminal B
IP6B
Input 6 terminal B
IP3A
Input 3 terminal A
IP7A
Input 7 terminal A
IP3B
Input 3 terminal B
IP7B
Input 7 terminal B
0-NO
Relay 0 Normally Open contact
4-NO
Relay 4 Normally Open contact
0-C
Relay 0 Common contact
4-C
Relay 4 Common contact
0-NC
Relay 0 Normally Closed contact
4-NC
Relay 4 Normally Closed contact
1-NO
Relay 1 Normally Open contact
5-NO
Relay 5 Normally Open contact
1-C
Relay 1 Common contact
5-C
Relay 5 Common contact
1-NC
Relay 1 Normally Closed contact
5-NC
Relay 5 Normally Closed contact
2-NO
Relay 2 Normally Open contact
6-NO
Relay 6 Normally Open contact
2-C
Relay 2 Common contact
6-C
Relay 6 Common contact
2-NC
Relay 2 Normally Closed contact
6-NC
Relay 6 Normally Closed contact
3-NO
Relay 3 Normally Open contact
7-NO
Relay 7 Normally Open contact
3-C
Relay 3 Common contact
7-C
Relay 7 Common contact
3-NC
Relay 3 Normally Closed contact
7-NC
Relay 7 Normally Closed contact
RELAY 7
RELAY 6
RELAY 5RELAY 4
RELAY 0RELAY 1RELAY 2RELAY 3
NO
C
NC
NO
C
NC
NO
C
NC
NO
C
NC
7
6
5
4
NO
C
NC
NO
C
NC
NO
C
NC
NO
C
NC
0
1
2
3
IP7B
IP7A
IP6B
IP6A
IP5B
IP5A
IP4B
IP4A
IP0A
IP0B
IP1A
IP1B
IP2A
IP2B
IP3A
IP3B
Strain Relief for Field Wiring

Switch & Sense 8/8 User's Guide Functional Details
11
Relay contact terminals (NO, C, NC (0) to NO, C, NC (7))
The two outer groups of 12 screw terminals connect to the normally open (NO), common (C), and normally
closed (NC) contacts for relays 0 through 7.
Form C relay output
A schematic for Form C relay contacts is shown here. The Form C relay has a C, NO, and NC contact.
Figure 4. Form C SPDT relay
When a (0) is written to the output bit, the C and NC are in contact.
When a (1) is written to the output bit, the C and NO are in contact.
At power-up, the relays are put into a non-energized state (NC in contact to Common).

Switch & Sense 8/8 User's Guide Functional Details
12
Relay contact protection circuit for inductive loads
If you are using the relays to control inductive loads, place a diode across the load terminals to suppress the
kickback voltage. If the diode is not present, the kickback voltage could cause the on-board processor to enter
an unstable state. To return the processor to a stable state, unplug the power cable from the Switch & Sense 8/8
and then reconnect.
A contact protection circuit is shown here. For AC loads, install a metal oxide varistor (MOV).
Figure 5. Relay contact protection circuit
Differential isolated digital input terminals (IP0A to IP7B)
Connect up to eight isolated digital input signals using the following screw terminal pairs:

IP0A and IP0B

IP4A and IP4B

IP1A and IP1B

IP5A and IP5B

IP2A and IP2B

IP6A and IP6B

IP3A and IP3B

IP7A and IP7B
A schematic of a single channel is shown below. Each signal is applied to a bridge rectifier so that the input is
not polarity sensitive. It can be driven by either AC (50 - 1000 Hz) or DC voltage.
The eight optically isolated (500 V) inputs can be read back as a single byte. Each input has a software-
controlled filter with a time constant of 5 ms (200 Hz). The filter is required for AC inputs and recommended
for almost all DC inputs. Unless you have a good reason to turn off a filter, we recommend that you enable it.
C
VInductive
Load Kickback
Diode
NC
+
-
NO
Relay

Switch & Sense 8/8 User's Guide Functional Details
13
Figure 6. Switch & Sense 8/8 single-channel configuration
The figure below shows a simple connection from a +9 V battery to the relay 4 terminals. When the relay is
energized, the relay 4 NO terminal connects the battery voltage to the input 4 terminal (IP4B).
Figure 7. Simple battery-to relay connection
The figure below shows the schematic of this connection.
Figure 8. Schematic of battery-to relay connection
1.6 K
Isolated Input
Not Polarized Circuitry Sharing
PC Ground
Filter Switch
0.1uF
47K
+5V
100K
IP4A
IP4B
NC
NO
C
+9 V

Switch & Sense 8/8 User's Guide Functional Details
14
Extending the input range
You can extend the input range beyond the 5 to 30 V specified by adding an external resistor. Figure 9 shows
the external resistor (Rext).
The equation Rext = 100 * (Vin – 30) calculates the resistor value for a given Vin.
Make sure the external resistor is capable of handling the power generated by the input. Calculate the power
requirement in watts (Pw) using the equation Pw= Rext/10000.
Figure 9. External resistor added to extend input range
1.6 K
V
in
Rext = 100 * (Vin – 30)
Pw= Rext/10000
Rext

15
Chapter 4
Specifications
Typical for 25 °C unless otherwise specified.
Specifications in italic text are guaranteed by design.
USB compliance
Device type
USB version 1.1 low speed (1.5 Mbs) device
Device compatibility
USB 1.1, USB 2.0
Power consumption
5 V USB Bus power
20 mA typical , 25 mA max.
External 9V unregulated supply
(Power supply included)
All relays off
30 mA typical, 40 mA max.
All relays on
500 mA typical, 625 mA max.
Power supply voltage range
7.5V – 20V
Output specification
Number
8
Contact configuration
8 FORM C (SPDT) NO, NC and Common available at connector
.
Contact rating
6 amperes (A) @ 120 volts AC (VAC) or 28 volts DC (VDC) resistive
Contact resistance
100 milliohms (mΩ) max
Operate time
10 milliseconds(ms) max
Release time
5 ms max
Vibration
10 to 55 hertz (Hz) (Dual amplitude 1.5 millimeters (mm))
Shock
10 G (11 ms)
Dielectric isolation
500 V (1 minute)
Life expectancy
10 million mechanical operations, min
Power on RESET state
Not energized. NC in contact to Common.
Isolated inputs
Number
8
Isolation
500 volts ( V)
Resistance
1.6K ohms (Ω) min.
Voltage range
DC
Input high: +5.0 VDC min or –5.0 VDC min
Input low: +1.5 VDC max. or –1.5VDC max.
Input range:

30 VDC max
AC (with filter)
Input high: 3.0 Vrms min (50-1000 Hz)
Input low: 1.5 Vrms max (50-1000 Hz)
Response
w/o filter
20 µs
w/ filter
5 ms
Filters
Time constant
5 ms (200 Hz)
Filter control
Software programmable at each input.
Power-up /reset
Filters off

Switch & Sense 8/8 User's Guide Specifications
16
USB connection
Captive pigtail cable
USB Type A connector
Length
2 meters
Environmental
Operating temperature range
0 to 70 °C
Storage temperature range
-40 to 100 °C
Humidity
0 to 95% non-condensing
Mechanical
Card dimensions
165 mm long x 150 mm wide x 20 mm high, 6.5 in. long x 5.9
in. widex 0.8 in. high
Case dimensions
185 mm long x 160 mm wide x 46 mm high, 7.3 in. long x 6.3
in. wide x 1.8 in. high
Case material
20 gage steel
Weight of complete unit
2.1 lbs.
Weight of card alone
0.6 lbs.
Screw terminal
Wire sizes
12-22 AWG
Miscellaneous
Case strain relief rating
20 lbs.
Screw terminal pinouts
Pin
Signal Name
Pin
Signal Name
IP0A
Input 0 terminal A
IP4A
Input 4 terminal A
IP0B
Input 0 terminal B
IP4B
Input 4 terminal B
IP1A
Input 1 terminal A
IP5A
Input 5 terminal A
IP1B
Input 1 terminal B
IP5B
Input 5 terminal B
IP2A
Input 2 terminal A
IP6A
Input 6 terminal A
IP2B
Input 2 terminal B
IP6B
Input 6 terminal B
IP3A
Input 3 terminal A
IP7A
Input 7 terminal A
IP3B
Input 3 terminal B
IP7B
Input 7 terminal B
0-NO
Relay 0 Normally Open contact
4-NO
Relay 4 Normally Open contact
0-C
Relay 0 Common contact
4-C
Relay 4 Common contact
0-NC
Relay 0 Normally Closed contact
4-NC
Relay 4 Normally Closed contact
1-NO
Relay 1 Normally Open contact
5-NO
Relay 5 Normally Open contact
1-C
Relay 1 Common contact
5-C
Relay 5 Common contact
1-NC
Relay 1 Normally Closed contact
5-NC
Relay 5 Normally Closed contact
2-NO
Relay 2 Normally Open contact
6-NO
Relay 6 Normally Open contact
2-C
Relay 2 Common contact
6-C
Relay 6 Common contact
2-NC
Relay 2 Normally Closed contact
6-NC
Relay 6 Normally Closed contact
3-NO
Relay 3 Normally Open contact
7-NO
Relay 7 Normally Open contact
3-C
Relay 3 Common contact
7-C
Relay 7 Common contact
3-NC
Relay 3 Normally Closed contact
7-NC
Relay 7 Normally Closed contact

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