Parallax 27113 User manual

Web Site: www.parallax.com
Forums: forums.parallax.com
Sales: [e-mail]
Technical: [e-mail]
Office: [phone]
Fax: [phone]
Sales: [phone]
Tech Support: [phone]
Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 1 of 13
Digital I/O Board Kit (#27113)
The Parallax Digital I/O Board Kit enables your microcontroller to interface to high voltage circuits
allowing you to read up to 8 optically isolated inputs and control up to 8 isolated outputs. Inputs can be
a voltage from 5-30VDC (AC compatible) and outputs can be either mechanical or solid state relays that
can switch up to 12A loads, such as cooling fans, solenoids, heating elements and more.
Simple parallel input/output control for ease of use or you can use the serial interface to minimize I/O pin
usage. The logic circuits operate from 3.3V to 5V making them compatible with most microcontrollers.
The ICs in the kit are all socketed making replacement easy should it ever be necessary. 8 green and 8
red LEDs indicate the status of input and outputs. 2 yellow LEDs indicate relay/logic power. Inputs can
be configured to handle a different range of input voltages by changing a couple of components.
Features
Mechanical or Solid State Relay output
Configurable Input Voltage range
Serial or parallel interface to inputs/outputs
LED indication of power and input/output status
AppMod compatible connection for Board of Education
Key Specifications
Power requirements: 12VDC @ 1A for relay power and 3.3 – 5VDC for logic power
Communication: Parallel or Synchronous Serial
Operating temperature: +32 to +158°F (0 to +70°C)
Dimensions: 7.25” L x 4.50” W x 1.00” H (184.1mm x 114.3mm x 25.4mm)
Application Ideas
Isolated power control of high voltage/current devices from your microcontroller, such as heating
elements, blower fans, solenoids, lighting systems and more
Isolated monitoring of high voltage signals such as doorbell, alarm or other signals.
Product Notices
Relays are not included with this kit and must be purchased separately. Mechanical Relays are
part #400-00052 and Solid State Relays are part #400-00053.
This product comes as a kit and must be assembled by the customer. Soldering experience is
required to assemble this kit and the following tools are required; Safety Glasses, Soldering Iron,
Solder, Flux (optional), Diagonal Cutters (to remove extra leads), Needle-Nosed Pliers (optional,
to bend/form leads)
This product is capable of switching high voltages. Observe the safety precautions listed in this
documentation.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 2 of 13
Bill of Materials
Part # Designator Description Quantity
200-01040 C1-C3 Capacitor, .1uF Monolithic, 100V, 10% 3
201-01075 C4 Capacitor, 1000uF, Electrolytic, 25V, 20% 1
350-00006 D1-D8 LED, Red T1-3/4 8
350-00007 D26, D28 LED, Yellow T1-3/4 2
350-00001 D9-D16 LED, Green T1-3/4 8
501-00006 D17-D24 Diode, 1N4004 Rectifier 8
501-00007 D25 Diode, Schottky, 40V/3A 1
179-00050 RN1 Resistor Network, 8-ISO, 1K, 1/4W, 2%, DIP-16 1
150-01020 R1-R8,R33,R42 Resistor, 1K, 1/4W, 5% 10
156-02235 R1_B-R8_B Resistor, 560, 1/4W, 5% 8
150-02210 R9-R16,R34 Resistor, 220, 1/4W, 5% 9
150-01030 R17-R24,R43 Resistor, 10K, 1/4W, 5% 9
156-02240 R25-R32 Resistor, 1.5K, 1/4W, 5% 8
602-01040 U1-U8 IC, 4N25 Optoisolator, DIP-6 8
500-00005 U9 IC, ULN2803 Darlington Array, DIP-18 1
602-00009 U10 IC, 74HC595 Shift Register, DIP-16 1
602-00010 U11 IC, 74HC165 Shift Register, DIP-16 1
452-00052 S1-S8 Socket, IC, DIP-16 8
452-00053 S9 Socket, IC, DIP-18 1
452-00054 S10-S11 Socket, IC, DIP-16 2
452-00012 J1-J17 2-Position Terminal Block 21
452-00007 J18 2.1mm DC Barrel Jack 1
452-00049 J19 2x10 (20-pin) Dual Row Header 1
452-00048 J20 2x5 (10-pin) Dual Row Header 1
451-00301 JP1 3-pin SIP Header 1
451-00201 JP2 2-pin SIP Header 1
452-00009 — Shorting Block (Shunt) 1
300-27113 PCB1 Raw PCB 1
Resources and Downloads
You may download free example programs, articles, videos etc. from the Digital I/O Board product page
on our website. Check back periodically for updates or additional examples including example programs,
customer applications, articles, etc.
http://www.parallax.com
Search for 27113 on our website.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 3 of 13
Assembly Instructions
Before starting assembly be sure you have the necessary tools and a clean area to work in. Start with
the lower profile components and work our way up to taller components.
Step 1:
Be sure the PCB is free
of dirt and excessive
fingerprints.
Set your board in a
position to start
installing and soldering
groups of components.
In the following steps
the component locations
will be highlighted with
a yellow square / circle.
Step 2:
Install Resistor Network
RN1 into the location
shown to the right. The
notch should be toward
the top. Solder this
device in carefully,
avoiding overheating the
component as will all
components from this
point.
Step 3:
Install the sockets, S1-
S8 and S9, S10 and S11
as shown to the right.
Notches should be
toward the top. Solder
these in place.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 4 of 13
Step 4:
Install and solder the
Yellow, Red and Green
LEDs in their respective
positions on the PCB as
shown. You may find it
easier to solder these
one at a time.
Step 5:
Install Diodes D17-D24
as shown to the right.
The components stand
on end in the right hole
with the stripe facing up
(as shown in the inset)
and the other lead bent
over into the left hole.
This is vertical
mounting of an axial
component.
Step 6:
If you will be using
input voltages outside
the range of 15-30VDC
then please skip this step
until you read the
section on ‘setting the
input voltage range’.
Install the 1.5K resistors
R25-R32 into the
positions shown at right.
Color code is: Brown,
Green, Red, Gold
Inset shows details.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 5 of 13
Step 7:
Install the 220 ohm
resistors R9-R16 and
R34 into the positions
shown at right.
Color code is: Red, Red,
Brown, Gold
Inset shows details.
Step 8:
Install the 10K resistors
R17-R24 and R43 into
the positions shown at
right.
Color code is: Brown,
Black, Orange, Gold
Inset shows details.
Step 9:
Install the 1K resistors
R1-R8, R33 and R42
into the positions shown
at right.
Color code is: Brown,
Black, Red, Gold
Inset shows details.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 6 of 13
Step 10:
Install the 560 ohm
resistors R1_B-R8_B
into the positions shown
at right.
Color code is: Green,
Blue, Brown, Gold
Install these in the same
manner as previous
resistors.
Step 11:
Install the headers
resistors J19, J20, JP1
and JP2 into the
positions shown at right.
Inset shows details.
Step 12:
Install the Terminal
Blocks J1-J17 (21 pcs
total) into the positions
shown at right.
Note: 12 Terminal
Blocks must be snapped
together for the relay
connections. These
slide together vertically
to create one long strip.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 7 of 13
Step 13:
Install the 2.1mm DC
Barrel Jack J18 into the
position shown at right.
Inset shows details.
Step 14:
Install Diode D25 into
the position shown at
right.
With the diode mounted
in the right (side with
square) the stripe should
be on the bottom. The
other lead should bend
over into the left hole.
Inset is from other side.
Step 15:
Install Capacitors C1-C4
into their respective
positions as shown at
right. Observe proper
polarity on C4. C1-C3
are non-polarized.
Inset shows details.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 8 of 13
Step 16:
If you have not already
done so you may now
install the ICs in their
respective slots. Be sure
the notches or pin 1
indicators are at the top
for all ICs. The
ULN2803 (U9) goes on
top, the 74HC595 (U10)
is in the middle and the
74HC165 (U11) is on
the bottom.
Step 17:
If you have not already
done so you may now
install the shorting
blocks (shunts). The
details for these are
covered later in this
documentation.
Inset shows detail for
JP1 (set for inverted
serial data).
Step 18:
Install the relays you
have chosen for your
application in any
position. Relays only
install in one direction
and you cannot mount
both types in the same
slot as they are
mechanically
interlocked. You do not
need to fill all slots to
use this board.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 9 of 13
Relay Selection (Mechinical or SSR)
The Digital I/O Board is capable of using Omron Mechanical Relays (#400-00052) or Sharp Solid State
Relays (#400-00053). You can use either relay in any of the eight available relay slots in any
combination. The slots are mechanically interlocked to prevent you from using both types in the same
position. The Mechanical Relays can switch up to 250VAC @ 12A (24VDC). The Solid State Relays can
switch up to 240VAC @ 8A (AC ONLY). Unlike the mechanical relays, solid state relays do not exhibit
contact noise or arcing. These Sharp Relays even provide zero-crossing detection to reduce switching
noise, however they can only switch AC voltage, not DC.
Relay Power
No matter which relays you use the Digital I/O Board requires a separate 12V @ 1A power supply for the
relays. This power is provided through 2.1mm Barrel Jack at the top left of the board or optionally via
the 2-position terminal block next to it. The terminal block is labeled + and – which the DC barrel jack is
center tip positive, making it compatible with our power supplies (Parallax recommends #750-00007).
Minimal reverse polarity protection is provided by diode D25.
Logic Power
The control logic requires power from the host microcontroller for the inputs to function. This will be
either 3.3V or 5V from your microcontroller provided to the VDD pin on the Digital I/O Board. Your
microcontroller’s ground should connect to the VSS pin. This allows the Digital I/O Board to operate at a
signal level compatible with your microcontroller. The V+ pin allows your microcontroller to get supply
voltage from the Digital I/O Board (reducing the need for an additional power supply). If your
microcontroller’s board has an on-board voltage regulator, you can obtain V+ from the Digital I/O Board
and then send your regulated output back to the VDD pin. V+ will be at the voltage of the relay supply
(typically ~12VDC).
Connecting and Testing (Parallel Interface)
Using the parallel interface (2x10 header) controlling relays is as simple as making a pin HIGH or LOW.
To energize a particular relay make its control pin HIGH. To turn it off bring that pin LOW. If your
microcontroller’s output pins are set to input the relays will also turn off due to internal pull-down
resistors within the ULN2803 IC. Inputs are easily read by reading a HIGH or LOW on their output pins
(labeled IN_1 through IN_8). Note that because the optocoupler inverts the signal, the pins will read
HIGH when that input is inactive and will read LOW when that input is active.
Note: Do not use the parallel and serial circuits at the same time. Use only one type of interface.
Connecting to an AppMod Header
The parallel interface (2x10 header) was designed to be compatible with the AppMod header on our
popular Board of Education development board. You could use a ribbon cable (not included) to connect
both boards together instantly connecting all necessary power and ground for a fully functioning parallel
control system.
When using the AppMod interface there are two additional considerations. You should use the I/O
declarations in the example code for the AppMod because the I/O pins are now mapped to specific pins
on the Digital I/O Board and these may not be what you expect. Also, the V+ connection allows the BoE
to get power from the Digital I/O Board. If you do not want this to happen you must remove the 2-pin
shunt from JP2 above the parallel interface. This disables the V+ pin on that header, but still allows the
BoE to provide 5V to VDD on the Digital I/O Board.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 10 of 13
Connecting and Testing (Serial Interface)
The serial interface (2x5 header) allows you to reduce the number of pins required to control the Digital
I/O Board by serially shifting data to/from the board over a synchronous serial interface. Whereas full
control requires 16 I/O pins using the parallel interface, the serial interface can provide full control with
as few as 4 I/O pins.
The pins labeled DATA_RLY, SCLK_RLY, LAT_RLY and /OE_RLY are connected to a 74HC595 serial to
parallel shift register. These pins have the following functions: DATA_RLY is serial data going out to the
shift register. This data is sent MSB first (8 bits) synchronously with the SCLK_RLY pin. On the BASIC
Stamp this can be achieved with the SHIFTOUT command. Once the data has been shifted out the
LAT_RLY pin must be pulsed to latch the data onto the outputs. /OE_RLY must be LOW in order for the
74HC595 to drive the relays. This can be tied to VSS or controlled via an I/O pin.
The pins labeled DIN, SCLK_IN and LOAD_IN are connected to a 74HC165 parallel to serial shift register.
These pins have the following functions: DIN is serial data from the shift register sent synchronously with
a clock pulse on SCLK_IN generated by the host microcontroller. On the BASIC Stamp this is achieved
with the SHIFTIN command. Before data is shifted in the current contents of the inputs must be loaded.
This is accomplished by pulsing the LOAD_IN line from HIGH to LOW and then back to HIGH. This line
must remain HIGH during shift operations and must only go LOW during a LOAD operation.
The DIN line has a 1K resistor in series to allow sharing of the 74HC165 data line with the 74HC595
DATA_RLY line. By connecting these lines together and also connecting SCLK_RLY to SCLK_IN you can
reduce the number of I/O pins required by your microcontroller down to four (4). In this configuration
LAT_RLY and LOAD_IN must have their own I/O pins and /OE_RLY can be connected to VSS. This circuit
provides a half-duplex system where you can access one shift register at a time. For full duplex
operation the DIN and DATA_RLY lines must be separate and for independent operation the SCLK_RLY
and SCLK_IN must also be separate.
Note: Do not use the parallel and serial circuits at the same time. Use only one type of interface.
Communication Protocol
The serial protocol (synchronous serial) used by the 74HC595 and 74HC165 is defined in more detail in
the datasheets for each device. BASIC Stamp users can also download the free PDF and example code
for the Stamp Works kit and review experiments 23 through 25 which deal with these shift registers both
independently and together.
Mode Jumper (JP1)
The 3-pin jumper just below the 74HC165 determines whether the data shifted in from the shift register
is inverted or not. Because the optocouplers inherently invert the data, when reading inactive inputs you
get all ones instead zeros which isn’t very intuitive. This jumper allows you to invert the data to
normalize the output and make it more intuitive. In the 1-2 position data is inverted and when an input
is active is will make its output go HIGH. With JP1 in the 2-3 position data is not inverted and when an
input is active you will get a LOW.
Note: The Parallel interface is unaffected by this jumper. Therefore the parallel signals from the
74HC165 are always inverted

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 11 of 13
Setting Input Voltage Range
This kit comes with 1.5K resistors on the inputs (R25-R32). These resistors were chosen as the defaults
based on a typical input voltage range of 15-30VDC (24 nominal). If you wish to input a different range
of voltages you will need a different resistor value in place of the default 1.5K unit. To calculate this
value it is necessary to have a few key pieces of information. First and foremost the Digital I/O Board is
configured to require a minimum of 8mA of current across an optocoupler LED for the output transistor to
trigger an output. Ideally you’ll probably set the current range for your input voltage to 10-20mA.
Given this range of current we can calculate the required resistor using the following math:
R = (VIN – VFWD) / ILED (where VFWD is the LED forward voltage, ILED is LED current and VIN is our input
voltage)
Assuming we want be able to input a 12V signal and accounting for the typical forward voltage for the
4N25 of 1.2V we can now calculate as follows:
R = (12V – 1.2V) / 0.01 = 1080
The closest value is 1K which will mean a current of 10.8mA @ 12V using I = (VIN – VFWD) / 1000
We can also calculate the maximum voltage we want on the input using a 1K resistor:
VINMAX = (1000 * 0.02) + 1.2 = 21.2V
Sensitivity
Because of the way the input LEDs are driven on the output, they will indicate voltage on an input even
when it is not sufficient to trigger and output. Voltage as low as 2V will cause the LED to start to glow,
however the output won’t trigger until the minimum current has been reached. This provides some
safety in the sense that you’ll have an indication of input voltage in spite of the outputs not being
triggered.
Precautions
As with any device capable of switching high voltages, precautions should always be taken to avoid
damage and/or injury. The following precautions are recommended in addition to any precautions by the
manufacturer of any equipment connected to this device.
The Digital I/O Board should be mounted inside a suitable enclosure or electrical panel using
standoffs. The board should not be able to move.
Any electrical connections to the board should be secured so they can not move and any wires
extending outside the enclosure should have strain relief.
Any incoming voltage rails to be switched by the relays should be fused prior to entering the
Digital I/O Board.
Always be sure any incoming voltage rails are powered off prior to connecting them to the Digital
I/O Board.
When connecting the V+ pin to VIN on another board, be sure that board does not have its own
power supply. The target board will now get power from the Digital I/O Board.

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 12 of 13
Specifications
Symbol Quantity Minimum Typical Maximum Units
V+ Relay Supply Voltage 9 12 15 V
VDD Logic Supply Voltage 3.3 — 5 V
ILED Input LED Forward Current 8 10 20 mA
IIDLE Idle Current (Relay Power Only, Off) — 10.5 — mA
Pin Definitions for 2x10 Header (Matches AppMod connector)
Pin Name Function
1 V+ Relay Power (Can be disconnected via JP2)
2 VDD Logic Power
3 RLY1 Relay 1 Control Line
4 RLY2 Relay 2 Control Line
5 RLY3 Relay 3 Control Line
6 RLY4 Relay 4 Control Line
7 RLY5 Relay 5 Control Line
8 RLY6 Relay 6 Control Line
9 RLY7 Relay 7 Control Line
10 RLY8 Relay 8 Control Line
11 IN_1 Input 1 Signal
12 IN_2 Input 2 Signal
13 IN_3 Input 3 Signal
14 IN_4 Input 4 Signal
15 IN_5 Input 5 Signal
16 IN_6 Input 6 Signal
17 IN_7 Input 7 Signal
18 IN_8 Input 8 Signal
19 VSS Ground
20 VSS Ground

Copyright © Parallax Inc. Digital I/O Board Kit (#27113) v1.0 2/19/2010 Page 13 of 13
Pin Definitions for 2x5 Header
Pin Name Function
1 V+ Relay Power (output to host controller)
2 VDD Logic Power (input from host controller)
3 DIN Serial Data In from 74HC165 (output to host controller)
4 DATA_RLY Serial Data Out to 74HC595 (input from host microcontroller)
5 SCLK_IN Synchronous Serial Clock (input from host microcontroller)
6 SCLK_RLY Synchronous Serial Clock (input from host microcontroller)
7 LOAD_IN Load Inputs (input from host microcontroller)
8 LAT_RLY Latch Relay Output (input from host microcontroller)
9 VSS Ground
10 /OE_RLY Relay Output Enable (input from host microcontroller)
Module Dimensions
Module Schematic
A full size schematic in PDF format is available from the product page on our website.

Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Parallax:
27113