Measurement Computing USB-ERB24 User manual

USB-ERB24
USB-based 24-Channel Electromechanical Relay Interface Device
June 2021. Rev 9
© Measurement Computing Corporation.
User's Guide

HM USB-ERB24.docx
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Notice
Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for
use in life support systems and/or devices without prior written consent from Measurement Computing
Corporation. Life support devices/systems are devices or systems that, a) are intended for surgical implantation
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 USB-ERB24............................................................................................................... 5
USB-ERB24 block diagram........................................................................................................................... 5
Chapter 2
Installing the USB-ERB24................................................................................................................... 6
Unpacking ..................................................................................................................................................... 6
Installing the software.................................................................................................................................... 6
Configuring the hardware switches................................................................................................................ 6
Relay control logic polarity switch (S1).................................................................................................................................6
Connecting the external power supply ........................................................................................................... 7
Installing the hardware .................................................................................................................................. 8
If your system does not detect the USB-ERB24....................................................................................................................8
Chapter 3
Functional Details ............................................................................................................................... 9
Components .................................................................................................................................................. 9
USB in connector ....................................................................................................................................................................9
USB out connector ..................................................................................................................................................................9
POWER IN connector...........................................................................................................................................................10
POWER OUT connector.......................................................................................................................................................10
USB LED...............................................................................................................................................................................10
PWR LED..............................................................................................................................................................................10
Invert/non-invert switch (S1)................................................................................................................................................10
Pull-up/down switch (S2)......................................................................................................................................................11
Screw terminals and relays ...................................................................................................................................................11
Relay configuration ..................................................................................................................................... 12
Relay contact protection circuit for inductive loads ............................................................................................................12
Daisy chaining additional relays to the USB-ERB24.................................................................................... 13
Power limitations using multiple USB-ERB24 devices ................................................................................ 13
Voltage drop ..........................................................................................................................................................................13
Chapter 4
Specifications.................................................................................................................................... 14
Output specifications ................................................................................................................................... 14
Power .......................................................................................................................................................... 14
External power input ................................................................................................................................... 15
External power output.................................................................................................................................. 15
USB specifications ...................................................................................................................................... 15
Relay contact pull-up/down option .............................................................................................................. 15
Mechanical .................................................................................................................................................. 16
Environmental ............................................................................................................................................. 16
Main connector............................................................................................................................................ 16
Screw terminal pinout.................................................................................................................................. 17
Declaration of Conformity................................................................................................................ 19

4
Preface
About this User's Guide
What you will learn from this user's guide
This user's guide describes the Measurement Computing USB-ERB24 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 USB-ERB24 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 USB-ERB24
The USB-ERB24 is a USB 2.0 full-speed device that provides the following features:
24 single-pole double-throw (SPDT) Form C electromechanical relays directly controlled by digital I/O
lines
Supports configurations as two banks of eight and two banks of four
Onboard switches to configure the logic polarity (active high or low) and power-on state for each relay
group.
Switch settings can be read back with software.
Screw terminals for field wiring connections with three connections to each relay – normally open (NO),
normally closed (NC), and common (C).
USB out and power out connections support powering and controlling multiple MCC USB devices that
support daisy-chaining from one external power source and one USB port in a daisy-chain configuration.1
Rugged enclosure that can mount on a DIN rail or on a bench
The USB-ERB24 is powered by an external 9 V regulated power supply that is shipped with the device.
USB-ERB24 block diagram
USB-ERB24 functions are illustrated in the block diagram shown here.
Figure 1. USB-ERB24 functional block diagram
1Depending on your load requirements, daisy chained devices may require a separate power supply.

6
Chapter 2
Installing the USB-ERB24
Unpacking
As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the device 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.
Contact us immediately if any components are missing or damaged.
Installing the software
Refer to the MCC DAQ Quick Start and the USB-ERB24 product page on our website for information about the
available software.
Install the software before you install your device
The driver needed to run the USB-ERB24 is installed with the software. Therefore, you need to install the
software package you plan to use before you install the hardware.
Configuring the hardware switches
The USB-ERB24 has banks of onboard switches that configure the relay logic polarity and relay power-up
state. Configure these switches before you connect the external power supply to the USB-ERB24. Factory-
configured default settings are listed in the table below. Refer to Figure 5 on page 9 for the location of each
switch.
Default switch configuration
Board label Description Default setting
INVERT NON-INVERT
S1
Configures the relay control logic parity per relay bank for invert or
non-invert logic.
Non-invert
Pull DOWN PULL UP
S2
Configures the relay power-on state per relay bank for pull-up or
pull-down.
Pull-down
Each DIP switch configures one relay group. The DIP switch labeled Aconfigures relays 1 to 8, the switch
labeled Bconfigures relays 9 to 16, the switch labeled CL configures relays 17 to 20, and the switch labeled CH
configures relays 21 to 24 (refer to Figure 2 below).
Figure 2. Typical board switch
Port A consists of relays 1 through 8, Port B consists of relays 9 through 16, Port CL consists of relays 17
through 20, and Port CH consists of relays 21 through 24.
Remove the device from the enclosure to access the onboard switches
To change the configuration of a switch, you must first remove the USB-ERB24 from the enclosure.

USB-ERB24 User's Guide Installing the USB-ERB24
7
Relay control logic polarity switch (S1)
Configure the Invert/non-invert switch (S1) to set the relay control logic polarity for each relay bank for invert
or non-invert. By default, this switch is shipped with all banks configured for non-inverted logic, as shown in
Figure 3.
Figure 3. Relay logic polarity switch S1
NON-INVERT mode: when "0" is written or read back through the USB bus, the relays are not energized.
INVERT mode: when "0" is written or read back through the USB bus, the relays are energized.
Switch settings for polarity can be read back using software through the USB bus. Switch settings for S1 do not
affect the power-on condition.
Relay power-on state switch (S2)
Configure the Pull-up/pull-down switch (S2) to set the state of each relay bank at power-up. By default, this
product is shipped with the switch for all banks configured for pull-down (relays inactive at power up), as
shown in Figure 4. Switch settings can be read back using software through the USB bus.
Figure 4. Resistor pull-up/down switch S2
PULL-UP: the relays are put into an energized state at power-up, regardless of the state of switch S1
PULL-DOWN: the relays are put into a non-energized state at power-up.
Connecting the external power supply
Power to the USB-ERB24 is provided with the 9 V, 3 A external power supply (CB PWR-9V3A). You must
connect the external power supply before connecting the USB connector to the USB-ERB24.
To connect the power supply to your USB-ERB24, complete the following steps:
1. Connect the external power cord to the power connector labeled POWER IN on the USB-ERB24 enclosure
(PWR IN on the board). Refer to Figure 5 for the location of this connector.
2. Plug the AC adapter into a power outlet.
The PWR LED turns on when 9 V power is supplied to the USB-ERB24. If the voltage supply is less than 6.0 V
or more than 12.5 V, the PWR LED does not turn on.
Do not connect external power to the POWER OUT connector
The power connector labeled POWER OUT on the enclosure (PWR OUT on the board) is used to provide power
to additional MCC USB devices. If you connect the external power supply to the POWER OUT connector, the
USB-ERB24 does not receive power, and the PWR LED does not turn on.

USB-ERB24 User's Guide Installing the USB-ERB24
8
Installing the hardware
To connect the USB-ERB24 to your system, complete the following steps.
1. Turn your computer on.
2. Connect the USB cable to the USB connector labeled USB IN on the USB-ERB24.
3. Connect the other end of the USB cable to a USB port on your computer or to an external USB hub that is
connected to your computer.
The USB LED turns on. Refer to Figure 5 on page 9 for the location of the USB LED.
Windows finds and installs the device driver automatically, and notifies you that the device is ready to use.
If the USB LED turns off
If communication is lost between the device and the computer, the USB LED turns off. To restore
communication, disconnect the USB cable from the computer and then reconnect it. This should restore
communication, and the USB LED should turn on.
If your system does not detect the USB-ERB24
If a USB device not recognized message displays when you connect the USB-ERB24, complete the following
steps:
1. Unplug the USB cable from the USB-ERB24.
2. Unplug the external power cord from the POWER IN connector on the enclosure.
3. Plug the external power cord back into the POWER IN connector.
4. Plug the USB cable back into the USB-ERB24.
Your system should now properly detect the USB-ERB24.
Contact technical support if your system still does not detect the USB-ERB24.
Caution! Do not disconnect any device from the USB bus while the computer is communicating with the
USB-ERB24, or you may lose data and/or your ability to communicate with the USB-ERB24.

9
Chapter 3
Functional Details
Components
The USB-ERB24 has the following internal components, as shown in Figure 5.
Two (2) USB connectors
Two (2) external power connectors
USB LED
PWR LED
Invert/non-invert switch (S1) — sets the relay control logic polarity
Pull-up/down switch (S2) — sets the relay power-on state
Screw terminals
1
USB output connector (USB OUT)
6
Invert/non-invert switch (S1)
2
USB input connector (USB IN)
7
USB LED
3 Power output connector (
POWER OU
T 8
PWR
LED
4
Power input connector (POWER IN)
9
Pull-up/down switch (S2)
5
Screw terminals
Figure 5. USB-ERB24 components
USB in connector
The USB in connector is labeled USB IN on the board and enclosure. This connector is a USB 2.0 full-speed
input connector that you connect to the USB port on your computer (or USB hub connected to your computer).
This connector supports USB 1.1 and USB 2.0 devices.
Hardware revision G and later are also compatible with USB 3.0 ports. The board revision may be determined
from the part number label on the enclosure that states "193773X-01L," where X is the board revision.
USB out connector
The USB out connector is labeled USB OUT on the board and enclosure. This connector is a downstream hub
output port intended for use with other MCC devices that support daisy chaining. The USB hub is self-powered,
and can provide 100 mA maximum current at 5 V.
For information on daisy chaining to other MCC USB devices, refer to Daisy chaining additional relays to the
USB-ERB24 on page 13.

USB-ERB24 User's Guide Functional Details
10
POWER IN connector
The USB-ERB24 requires between 6.0 V and 12.5 V of external power. An external power connection is
required to activate the relays and to run tests in InstaCal.
To supply external power, connect the POWER IN connector to the supplied +9 V external power supply
(CB PWR-9V3A).
POWER OUT connector
Use the POWER OUT connector to provide power to additional daisy chained MCC USB devices from a single
external power supply. Depending on your load requirements, daisy chained products may require a separate
power supply. Refer to Power limitations using multiple USB-ERB24 devices on page 13 for more information.
A user-supplied custom cable is required to daisy chain multiple devices.
USB LED
The USB LED indicates the communication status of the USB-ERB24. It uses up to 5 mA of current and cannot
be disabled. The table below explains the USB LED function.
USB LED Indications
USB LED Indication
On
The USB-ERB24 is connected to a computer or external USB hub.
Blinking
Initial communication is established between the USB-ERB24 and the computer, or data is being
transferred.
PWR LED
The USB-ERB24 incorporates an onboard voltage supervisory circuit that monitors the external 9 V power. If
the input voltage falls outside of the specified range, the PWR LED shuts off. The table below explains the
function of the PWR LED.
PWR LED Indications
PWR LED Indication
On
External power is supplied to the USB-ERB24.
Off
Power is not supplied by the external supply, or a power fault has occurred. A power fault occurs
when the input power falls outside of the specified voltage range of the external supply
(6.0 V to 12.5 V).
Invert/non-invert switch (S1)
The Invert/non-invert switch (S1) sets the relay control logic per relay bank to either inverted or non-inverted.
By default, switch S1 is configured for non-invert (see Figure 6).
Figure 6. Switch S1 default configuration