Switch & Sense 8/8
USB-based Isolated Input and Relay Output

User's GuideMay 2021. Rev 8© Measurement Computing Corporation

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Switch-Sense-8-8.docx

2

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 .................................................................................................. 5Overview: 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 ............................................................................................................................... 8External components ..................................................................................................................................... 8
Direct current (dc) power connector and +9 V power supply ............................................................................................... 8External power LED................................................................................................................................................................ 9
Status LED............................................................................................................................................................................... 9USB connector......................................................................................................................................................................... 9Internal components ...................................................................................................................................... 9Screw terminals and relays ..................................................................................................................................................... 9Main 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 4Specifications.................................................................................................................................... 15
USB compliance .......................................................................................................................................... 15Power consumption ..................................................................................................................................... 15
Output specification..................................................................................................................................... 15
Isolated inputs ............................................................................................................................................. 15
USB connection........................................................................................................................................... 16
Environmental ............................................................................................................................................. 16
Mechanical .................................................................................................................................................. 16
Screw terminal............................................................................................................................................. 16
Miscellaneous .............................................................................................................................................. 16
Screw terminal pinouts ................................................................................................................................ 16

3

Preface

About this User's Guide
What you will learn from this user's guideThis 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: techsupport@mccdaq.com
Phone: 508-946-5100 and follow the instructions for reaching Tech Support

For international customers, contact your local distributor. Refer to the International Distributors section on ourwebsite at www.mccdaq.com/International.

4

Introducing the Switch & Sense 8/8

Chapter 1

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 anddisabled by software control.
The Switch & Sense 8/8 is shown here. All I/O connections are made to four sets of screw terminals.

5

Switch & Sense 8/8 User's Guide

Introducing the Switch & Sense 8/8

Functional block diagram

Control

Differential
Isolated Inputs

Switch & Sense 8/8 functions are illustrated in the block diagram shown here.

ControlRegisters

9 VDC externalpower supply

Control

Relays 0 to 7

FORM C
Relay Outputs

ControlBusUSBController

9VD+USB
HOST(1.5 MBS)

Universal Serial Bus

Figure 1. Switch & Sense 8/8 functional block diagram

6D-VccGndInstalling the Switch & Sense 8/8

Chapter 2

UnpackingAs with any electronic device, you should take care while handling to avoid damage from staticelectricity. 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 softwareRefer 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 thesoftware 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 thevoltage 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 toinstall 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 anavailable USB port on the computer or to an external USB hub connected to the computer. Connect the otherend 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.

7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

Direct Current
power connection(7.5 to 20 V)
STATUSLEDEXTERNAL POWER
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 therelays 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 tothis connector.

8

Switch & Sense 8/8 User's Guide

Functional Details

External power LED
The LED labeled EXTERNAL POWER lights up when the Switch & Sense 8/8 is connected to an externalpower 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 ofcurrent and cannot be disabled.
Status LED illumination
LED Illumination

IndicationSteady green
Blinks continuously
Blinks three times

The Switch & Sense 8/8 is connected to a computer or external USB hub.
Data is being transferred.
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, andtwo 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 toterminate any of the input or output signals.

9Functional Details

NCNOC 5NC
NOC 4NC

Strain Relief for Field Wiring

NO0 C
NCNO
1 CNC
NO
2 CNC
NO
3 CNC

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

PinIP0A
IP0B
IP1A
IP1B
IP2A
IP2B
IP3A
IP3B
0-NO
0-C
0-NC
1-NO
1-C
1-NC
2-NO
2-C
2-NC
3-NO
3-C
3-NC

Signal Name
Input 0 terminal A
Input 0 terminal B
Input 1 terminal A
Input 1 terminal B
Input 2 terminal A
Input 2 terminal B
Input 3 terminal A
Input 3 terminal B
Relay 0 Normally Open contact
Relay 0 Common contact
Relay 0 Normally Closed contact
Relay 1 Normally Open contact
Relay 1 Common contact
Relay 1 Normally Closed contact
Relay 2 Normally Open contact
Relay 2 Common contactRelay 2 Normally Closed contact
Relay 3 Normally Open contact
Relay 3 Common contact
Relay 3 Normally Closed contact

PinIP4A
IP4B
IP5A
IP5B
IP6A
IP6B
IP7A
IP7B
4-NO
4-C
4-NC
5-NO
5-C
5-NC
6-NO
6-C
6-NC
7-NO
7-C
7-NC

10Signal Name
Input 4 terminal A
Input 4 terminal B
Input 5 terminal A
Input 5 terminal B
Input 6 terminal A
Input 6 terminal B
Input 7 terminal A
Input 7 terminal B
Relay 4 Normally Open contact
Relay 4 Common contact
Relay 4 Normally Closed contact
Relay 5 Normally Open contact
Relay 5 Common contact
Relay 5 Normally Closed contact
Relay 6 Normally Open contact
Relay 6 Common contact
Relay 6 Normally Closed contact
Relay 7 Normally Open contact
Relay 7 Common contact
Relay 7 Normally Closed contact

RELAY 1IP0A
IP0B
IP1A
IP1B
IP2A
IP2B
IP3A
IP3B

IP7B
IP7A
IP6B
IP6A
IP5B
IP5A
IP4B
IP4A

RELAY 2NO
C 7
NCNO
C 6

RELAY 3

RELAY 4RELAY 5RELAY 6RELAY 7

RELAY 0Switch & Sense 8/8 User's Guide

Switch & Sense 8/8 User's Guide

Functional Details

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 normallyclosed (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).

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Switch & Sense 8/8 User's Guide

Functional Details

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 thekickback 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).
RelayNOCNC+V-Inductive
LoadKickback
DiodeFigure 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
IP1A and IP1B
 IP2A and IP2B
 IP3A and IP3B

IP4A and IP4B
IP5A and IP5B
 IP6A and IP6B
 IP7A and IP7B



A schematic of a single channel is shown below. Each signal is applied to a bridge rectifier so that the input isnot 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 softwarecontrolled 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.

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Switch & Sense 8/8 User's Guide

Functional Details+5V100K
1.6 K

47K

Filter Switch
0.1uF

Isolated Input
Not Polarized

Circuitry Sharing
PC GroundFigure 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 isenergized, 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.
IP4BNOC+9 V
IP4ANC

Figure 8. Schematic of battery-to relay connection

13Switch & Sense 8/8 User's Guide

Functional Details

Extending the input range
You can extend the input range beyond the 5 to 30 V specified by adding an external resistor. Figure 9 showsthe 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.
R ext

1.6 K

V in
R ext = 100 * (V in – 30)
P w = R ext/10000

Figure 9. External resistor added to extend input range

14Chapter 4Specifications
Typical for 25 °C unless otherwise specified.
Specifications in italic text are guaranteed by design.

USB complianceDevice type
Device compatibility

USB version 1.1 low speed (1.5 Mbs) device
USB 1.1, USB 2.0

Power consumption
5 V USB Bus power
External 9V unregulated supply(Power supply included)
Power supply voltage range

20 mA typical , 25 mA max.
All relays off
30 mA typical, 40 mA max.
All relays on
500 mA typical, 625 mA max.
7.5V – 20V

Output specification
NumberContact configuration
Contact rating
Contact resistanceOperate time
Release timeVibration
Shock
Dielectric isolation
Life expectancy
Power on RESET state

88 FORM C (SPDT) NO, NC and Common available at connector.
6 amperes (A) @ 120 volts AC (VAC) or 28 volts DC (VDC) resistive
100 milliohms (mΩ) max
10 milliseconds(ms) max
5 ms max
10 to 55 hertz (Hz) (Dual amplitude 1.5 millimeters (mm))
10 G (11 ms)
500 V (1 minute)10 million mechanical operations, min
Not energized. NC in contact to Common.

Isolated inputs
NumberIsolation
Resistance
Voltage range

8500 volts ( V)
1.6K ohms (Ω) min.
DCAC (with filter)
Response
Filters

w/o filter
w/ filter
Time constant
Filter control
Power-up /reset

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
Input high:
3.0 Vrms min (50-1000 Hz)
Input low:
1.5 Vrms max (50-1000 Hz)
20 µs
5 ms
5 ms (200 Hz)
Software programmable at each input.
Filters off15

Switch & Sense 8/8 User's GuideSpecifications

USB connection
Captive pigtail cableLength

USB Type A connector
2 metersEnvironmental
Operating temperature range
Storage temperature range
Humidity

0 to 70 °C-40 to 100 °C
0 to 95% non-condensing

Mechanical
Card dimensions
Case dimensions
Case material
Weight of complete unit
Weight of card alone

165 mm long x 150 mm wide x 20 mm high, 6.5 in. long x 5.9
in. widex 0.8 in. high
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
20 gage steel
2.1 lbs.
0.6 lbs.

Screw terminal
Wire sizes

12-22 AWG

Miscellaneous
Case strain relief rating

20 lbs.

Screw terminal pinouts
PinIP0A
IP0B
IP1A
IP1B
IP2A
IP2B
IP3A
IP3B

Signal Name
Input 0 terminal A
Input 0 terminal B
Input 1 terminal A
Input 1 terminal B
Input 2 terminal A
Input 2 terminal B
Input 3 terminal A
Input 3 terminal B

Pin
IP4A
IP4B
IP5A
IP5B
IP6A
IP6B
IP7A
IP7B

Signal Name
Input 4 terminal A
Input 4 terminal B
Input 5 terminal A
Input 5 terminal B
Input 6 terminal A
Input 6 terminal B
Input 7 terminal A
Input 7 terminal B

0-NO
0-C0-NC
1-NO
1-C
1-NC
2-NO
2-C
2-NC
3-NO
3-C
3-NC

Relay 0 Normally Open contact
Relay 0 Common contact
Relay 0 Normally Closed contact
Relay 1 Normally Open contact
Relay 1 Common contact
Relay 1 Normally Closed contact
Relay 2 Normally Open contact
Relay 2 Common contact
Relay 2 Normally Closed contact
Relay 3 Normally Open contact
Relay 3 Common contact
Relay 3 Normally Closed contact

4-NO
4-C
4-NC
5-NO
5-C
5-NC
6-NO
6-C
6-NC
7-NO
7-C
7-NC

Relay 4 Normally Open contact
Relay 4 Common contact
Relay 4 Normally Closed contact
Relay 5 Normally Open contactRelay 5 Common contact
Relay 5 Normally Closed contact
Relay 6 Normally Open contact
Relay 6 Common contact
Relay 6 Normally Closed contact
Relay 7 Normally Open contact
Relay 7 Common contact
Relay 7 Normally Closed contact

16

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