B&B Electronics 485SDD16 User Manual

RS-485 Digital I/O Module

Model 485SDD16

Document ation Number 485SDD16-1005

Designed and Manufactured

of domestic and imported parts by

B&B Electronics Mfg. Co. Inc.

707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350

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[e-mail]

 B&B Electronics -- Revised February 2005

pn#3605-r1

This product

In Ottawa, Illinois

USA

Internet:

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Table of Contents

Chapter 1- Introduction........................................... 1

485SDD16 Features............................................... 1

Packing List............................................................2

485SDD16 Specifications....................................... 2

I/O Lines................................................................................2

Inputs.................................................................................2

Outputs..............................................................................2

Power Supply........................................................................3

Communications ...................................................................3

Size .......................................................................................3

Chapter 2 - Connections......................................... 5

Digital I/O Connections........................................... 5

Digital Inputs ..... ....................................................................5

Digital Outputs.......................................................................5

Ground ..................................................................................5

Serial Port Connections.......................................... 6

Power Supply Connections..................................... 8

Chapter 3 - Commands........................................... 9

Syntax .................................................................. 10

I/O Data Bytes...... .............................. .................................10

Read I/O Lines Command.................................... 12

Set Output Lines Command................................. 12

Set Module Address Command............................ 13

Set Turn-around Delay Command........................ 13

Define I/O Lines Command..................................14

Set Power-up States Command........................... 15

Read Configuration Command............................. 15

Chapter 4 - I/O Interfacing..................................... 17

Digital Inputs......................................................... 17

Digital Outputs...................................................... 19

Chapter 5 - Software.............................................. 21

Programming Techniques.....................................21

Read I/O Lines Command ..................................................21

Read Configurat ion Command ...........................................22

Set Output States Command..............................................24

Define I/O Lines Command.................................................25

Set Power-up States Command .........................................26

Set Module Address Command..........................................27

Set Turn-around Delay Command........................ ..............28

Demonstration Program ....................................... 29

Hard Drive Installation .......... Error! Bookmark not defined.

Running Demonstration Program .......................................29

APPENDIX A..........................................................A-1

ASCII Character Codes.......................................A-1

APPENDIX B..........................................................B-1

Hexadecimal/Decimal Conversions.....................B-1

APPENDIX C..........................................................C-1

Interface Modules for SDD16 Models..................C-1

DTB25.................................................................C-2

DBM16 ................................................................C-3

DBM16 Interfacing ............................................................C-4

Inputs.............................................................................C-5

Outputs..........................................................................C-7

DBM16 Specificat ions.......................................................C-8

I/O Lines ........................................................................C-8

Inputs .........................................................................C-8

Outputs ......................................................................C-8

Power Supply ................................................... .............C-8

Size................................................................................C-8

Appendix D

Adding Data Field Confirmation.........................D-1

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Chapter 1- Introduction

485SDD16 Features

The 485SDD16 is a general purpose control module that
operates through an RS-485 interface. The 485SDD16 offers 16
discrete digital I/O lines. With these features, the module can be
used to sense external ON/OFF conditions and to control a variety
of devices.
Each of the sixteen I/O lines can be defined as either an input or
an output. The digital outputs are CMOS compatible. The digital
inputs are CMOS/TTL compatible. The digital I/O lines are available
through a DB-25S (female) connector.

The 485SDD16 connects to the host computer’s RS-485 or RS­422 serial port using terminal blocks. The address and turn-around
delay are software programmable to allow for use of multiple
devices or connection to existing multi-node systems. The unit
automatically detects baud rates from 1200 to 9600. A data format
of 8 data bits, 1 stop bit and no parity is used.
Configuration parameters are stored in non-volatile memory.
These parameters consists of module address, communication turn­around delay, I/O definitions, and output power-up states.

The unit is powered by connecting +12Vdc to terminal blocks or
to the DB-25S I/O connector.

Figure 1.1 - 485SDD16 Module

Figure 1.2 - Simplified Block Diagram

Packing List

Examine the shipping carton and contents for physical damage.
The following items should be in the shipping carton:

1. 485SDD16 unit

2. Software

3. This instruction manual
If any of these items are damaged or missing contact B&B
Electronics immediately.

485SDD16 Specifications

I/O Lines

Total: 16 (Factory default = inputs)

Inputs

Voltage Range: 0 Vdc to 5 Vdc
Low Voltage: 1.0 Vdc max.
High Voltage: 2.0 Vdc min.
Leakage Current: 1 microamp max.

Outputs

Low Voltage: 0.6 Vdc @ 8.3 milliamps (Sink)
High Voltage: 4.3 Vdc @ -3.1 milliamps (Source)

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Power Supply

Input Voltage: 8 Vdc to 16 Vdc @ 35 milliamps

(Doesn’t include the power
consumption of external devices.)

Connection: Terminal Blocks or DB-25S

Communications

Standard: RS-422/485
Addresses: 256 (Factory default = 48 decimal)
Turn-around Delay: Software programmable from 0 to
255 character transmission times.
(Factory default = 1)

Baud Rate: 1200 to 9600 (automatic detection)
Format: 8 data bits, 1 stop bit, no parity
Connection: Terminal Blocks
Optical Isolation: If optical isolation is required, use B&B’s
485HSPR high-speed optically isolated converter with this product.

Size 0.7" x 2.1" x 5.2"

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Chapter 2 - Connections

This chapter will cover the connections required for the
485SDD16. There are three sets of connections: digital I/O, serial
port, and power supply. Do not make any connections to the
485SDD16 until you have read this chapter.

Digital I/O Connections

Connections to the I/O lines are made through the DB25S
(female) I/O port connector. Refer to Table 2.1. See Chapter 5 for
I/O interfacing examples.

Digital Inputs

The digital input lines are CMOS/TTL compatible and can handle
voltages from 0Vdc to +5Vdc.

Digital Outputs

The digital output lines have a maximum voltage of +5Vdc and
are CMOS compatible.

Ground

This pin should be connected to the external digital devices
ground.

Table 2.1 - 485SDD16 I/O Port Pinout

DB-25S

Pin #

10 I/O #1 23 I/O #7
11 I/O #2 24 I/O #6
12 I/O #3 25 I/O #5
13 I/O #4

Function

DB-25S

Pin #

Function

1 No connection 14 I/O #15
2 No connection 15 I/O #14
3 No connection 16 I/O #13
4 No connection 17 I/O #12
5 No connection 18 I/O #11
6 No connection 19 I/O #10
7 Ground 20 No connection
8 +12Vdc Input 21 I/O #9
9 I/O #0 22 I/O #8

Serial Port Connections

In order to communicate to the 485SDD16 module it must be
connected to an RS-422/RS-485 serial port. The 485SDD16 will
work on a 2-wire or 4-wire RS-485 multi-node network. Refer to
B&B Electronics’ free RS-422/485 Application Note for more
information. The unit automatically detects baud rates from 1200 to

9600. A data format of 8 data bits, 1 stop bit and no parity is used.
Connections are made using terminal blocks. Table 2.2 shows the
terminal blocks and their functions.

Table 2.2 - RS-485 Terminal Block Connections

TB

Label

FR

GND

TD(A) Transmit

TD(B) Transmit

RD(A) Receive

RD(B) Receive

+12V +12 Vdc

GND Ground - Connection for Signal GND and

Signal

Frame
Ground

Data (A)

Data (B)

Data (A)

Data (B)

Power

Signal

Direction at

485SDD16

- Connection for frame ground.

Output Connection is required. [Loop to

RD(A) for 2-wire hookup]

Output Connection is required. [Loop to

RD(B) for 2-wire hookup]

Input Connection is required. [Loop to

TD(A) for 2-wire hookup]

Input Connection is required. [Loop to

TD(B) for 2-wire hookup]

Input Connection is required.

Power Supply GND.

A typical 2-wire RS-485 connection is shown in Figure 2.3 and a

typical RS-422 (or RS-485 4-wire) connection is shown in Figure

2.4. Note that the 485SDD16 data line labels use “A” and “B”
designators (per EIA RS-485 Specification). However, some RS-485
equipment uses “+” and “-“ as designators. In almost all cases, the
“A” line is the equivalent of the “-“ line and the “B” is the equivalent of
the “+” line. With an RS-485/422 system there are other factors that
require consideration, such as termination and turn-around delay.
For more information refer to B&B Electronics’ free RS-422/485
Application Note.

Notes

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Figure 2.1 - Example of Multi-Node Network

485SDD16 485SDD16485SDD16

Power Supply Connections

Power to the 485SDD16 must be supplied by an external power

Figure 2.3 - RS-422 4-wire Connection

supply connected to the +12Vdc and GND terminal blocks or to the
I/O connector. An external power supply must be able to supply 8 to
16 Vdc at 35ma.

NOTE: Power requirements of the module does not include the
power consumption of any external devices connected to the
module. Therefore, any current that is sourced by the digital outputs
must be added to this value and the current must not exceed the
maximum output source current. Refer to the 485SDD16
Specification Section of Chapter 1.

Figure 2.2 - RS-485 2-wire Connection

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Chapter 3 - Commands

There are only two commands required to control the 485SDD16:
set output lines, and read I/O lines. Five additional commands are
used for configuring the module: set module address, set turn­around delay, define I/O lines, set power-up states, and read
configuration. Command strings are from four to six bytes in length:
the “!” character, an address byte, two command characters, and
one or two data bytes (if required). (See Table 3.1).

Table 3.1 - 485SDD16 Commands

Function Command Response
Read I/O Lines !{addr}RD {I/O msb}{I/O lsb}

Set Output Lines !{addr}SO{I/O msb}{I/O

Set Module Address !{addr}SA{new adr} no response
Set Turn-around
Delay
Define I/O Lines !{addr}SD{I/O msb}{I/O lsb} no response
Set Power-up States !{addr}SS{I/O msb}{I/O lsb} no response

Read Configuration !{addr}RC

lsb}

!{addr}SC{#} no response

Symbols: {...} represents one byte

<...> represents a numeric value

Before going into the specifics of each command, it is important
to understand that a byte has a numeric value from 0 to 255. The
byte's value can be represented in decimal (0 - 255) format,
hexadecimal (00 - FF) format, binary (00000000 - 11111111) format,
or as an ASCII character. The fixed bytes of each command will be
represented as ASCII characters. For example the Read I/O
command contains the following ASCII characters: “!" and "RD”.
Refer to Table 3.1. However, it is important to remember that an
ASCII character has a numeric value. Example: the ASCII "0" (zero)
does not have a numeric value of zero but has a value of 48. The
decimal and hexadecimal equivalents of some ASCII characters are
shown in Table 3.2. Some commands require additional data bytes
to complete the command. These data bytes may be represented in
any of the formats list above. Refer to Appendix A for more ASCII
and decimal equivalents.

no response

I/O Definitions
{I/O msb}{I/O lsb}
Power-up States
{I/O msb}{I/O msb}
RS-485 Config.
{addr}{t-a delay}

Table 3.2 - Equivalent Values

ASCII Decimal Hexadecimal

! 33 21h
0 48 30h
A 65 41h

C 67 43h
D 68 44h
O 79 4Fh
R 82 52h
S 83 53h

Syntax

Command strings consist of four to six bytes. The first byte is the
start of message byte. The start of message byte is always the
ASCII “!” character. The second byte is the address byte. This byte
allows each unit to have a unique address. The factory default
address is the ASCII "0" character. The next two bytes are the
command characters. These bytes are ASCII characters and used
to specify which command will be executed by the module. Some
commands require an argument field containing a fifth and
sometimes a sixth data byte. Commands that manipulate I/O lines
require two data bytes, a Most Significant and a Least Significant
data byte respectively.

Command Syntax: !
| | | | | |
| | | | | 6th Data Byte
| | | | 5th Data Byte
| | | 2nd Command Byte
| | 1st Command Byte
| Address Byte
Start of Message Byte

I/O Data Bytes

When constructing commands to manipulate output lines or
when reading the state of the I/O lines it is necessary to know how to
select and interpret the I/O data bytes. The sixteen I/O lines are
represented by two data bytes. The Most Significant data byte
represents I/O lines #15 through #8 and the Least Significant data
byte represents I/O lines #7 through #0. The Most Significant byte is
always sent and received first followed by the Least Significant byte.

0 _ _ _ _

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A byte represents an eight-bit binary number (11111111),
therefore each byte can represent eight I/O lines. Each bit is
assigned a bit position and a weight (value). Refer to Table 3.3.

Table 3.3 - Bit Assignments for I/O Lines

MOST SIGNIFICANT I/O BYTE

I/O Line # 15 14 13 12 11 10 9 8

Bit Position 7 6 5 4 3 2 1 0

Hex Weight 80 40 20 10 8 4 2 1

Dec. Weight 128 64 32 16 8 4 2 1

LEAST SIGNIFICANT I/O BYTE

I/O Line # 7 6 5 4 3 2 1 0

Bit Position 7 6 5 4 3 2 1 0

Hex Weight 80 40 20 10 8 4 2 1

Dec. Weight 128 64 32 16 8 4 2 1

To set an output to a HIGH state the corresponding bit position
must be set to a "1". Conversely to set an output LOW the
corresponding bit position must be set to a "0". When reading I/O
lines, any bit set to a "0" indicates the corresponding I/O line is in
the LOW state and any bit set to a "1" indicates the corresponding
I/O line is in the HIGH state.

Example 3.1 - To set outputs 15, 8, 1, and 0 to a HIGH state, and all

other outputs to a LOW state (shown in bold face) -

MS Byte LS Byte

Shown in binary -

Shown in decimal -

Shown in hexadecimal -

10000001

129

(128+1)

81

(80h+1h)

Example 3.2 - Reply from Read I/O command (shown in bold face) -

MS Byte LS Byte

Shown in binary -

Shown in decimal -

Shown in hexadecimal -

11001000

200

(128+64+8)

C8

(80h+40h+8h)

I/O lines #15, 14, 11, 6, 4, 1 are HIGH and all other I/O lines are
LOW.

00000011

(2+1)

(2h+1h)

01010010

(64+16+2)

(40h+10h+2h)

3

3

82

52

Read I/O Lines Command

The Read I/O Lines command returns two data bytes that reflect
the state of the I/O lines. The first data byte contains the most
significant I/O lines (15 - 8). The second data byte contains the least
significant I/O lines (7 - 0). If a bit is a "0" then the state of that I/O
line is LOW. If a bit is a "1" then the state of that I/O line is HIGH.

Command: !{addr}RD
Argument: none
Response: the state of the 16 I/O lines in two 8 bit bytes. (shown in
bold face)
ASCII Example: !0RDÈR
Dec. Example: !0RD<200><82>
Hex. Example: !0RD<C8><52>
Bin. Example: !0RD<11001000><01010010>
Description: Read module 0's (decimal 48) I/O lines. The first byte
indicates that I/O lines #15, 14, & 11 are HIGH and I/O lines # 13,
12, 10, 9, & 8 are LOW; the second byte indicates that I/O lines # 6,
4, & 1 are HIGH and I/O lines # 7, 5, 3, 2, & 0 are LOW.

Set Output Lines Command

The Set Output Lines command is used to set the states of the
output lines. This command requires two data bytes. These data
bytes specify the output state of each output line. The first data byte
represents the most significant I/O lines (15 - 8). The second data
byte represents the least significant I/O lines (7 - 0). If a bit position
is set to a "0" then the state of that output line will be set LOW. If a
bit position is set to a "1" then the state of that output line will be set
HIGH.
NOTE: Refer to the "Define I/O Lines" command to define an I/O line
as an output.

Command: !{addr}SO
Argument: {I/O msb}{I/O lsb}
Response: none
ASCII Example: !0SOUA
Dec. Example: !0SO<85><65>
Hex. Example: !0SO <55><41>
Bin. Example: !0SO<01010101><01000001>
Description: Set module 0's (decimal 48) output lines. The first byte
sets output lines #14, 12, 10, & 8 HIGH and output lines #15, 13,
11, & 9 LOW; the second byte sets output lines #6, & 0 HIGH and
output lines # 7, 5, 4, 3, 2, & 1 LOW. Note: If any of these lines are
defined as inputs the bit settings are ignored.

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Set Module Address Command

The Set Module Address command is used to change the
address of a 485SDD16. This commands requires one data byte.
This data byte is used to specify the module's new address.
Addresses can be assigned any decimal value from 0 to 255. The
address is stored in non-volatile memory and is effective
immediately. Each module must be assigned its own unique
address when connected to an RS-485 muti-node network.

Command: !{addr}SA
Argument: {new address}
Response: none
ASCII Example: !0SA9
Dec. Example: !0SA<57>
Hex. Example: !0SA<39>
Bin. Example: !0SA<00111001>
Description: Change module address from ASCII "0" (48 decimal) to
address ASCII "9" (57 decimal).

Set Turn-around Delay Command

The Set Turn-around Delay command sets the amount of time
the 485SDD16 waits before transmitting its response. This ensures
that no two drivers are enabled at the same time on a two-wire RS­485 network. The turn-around delay is stored in non-volatile
memory. This command requires a data byte that specifies the turn­around delay. Where {turn-around delay} is a number from 0 to 255.
One unit of turn-around is equal to one character transmission time.
The turn-around delay can be computed as follows:

character time = (1 / baud rate) * 10

Command: !{addr}SC
Argument: {turn-around delay}
Response: none
ASCII Example: !9SC♦
Dec. Example: !9SC<04>
Hex. Example: !9SC<04>
Bin. Example: !9SC<00000100>
Description: Set module 9's (decimal 57) turn-around delay to four
character transmission times (@ 9600 baud the turn-around delay =

4.17ms).

turn-around delay = character time * data byte

Define I/O Lines Command

The Define I/O Lines command is used to define each of the 16
I/O lines as either an input or an output. This command requires two
data bytes. Each data byte defines eight I/O lines. The first data
byte defines the eight most significant I/O lines (15 - 8). The second
data byte defines the eight least significant digital I/O lines (7 - 0). If
a bit position is set to a "0" then the I/O line will defined as an input.
If a bit position set to a "1" then the I/O line will be defined as an
output.

Command: !{addr}SD
Argument: {I/O msb}{I/O lsb}
Response: none
ASCII Example: !0SDUA
Dec. Example: !0SD<85><65>
Hex. Example: !0SD<55><41>
Bin. Example: !0SD<01010101><01000001>
Description: Define module 0's (decimal 48) I/O lines. The first byte
define I/O lines #14, 12, 10, & 8 as outputs and I/O lines #15, 13,
11, & 9 as inputs; the second byte define I/O lines #6, & 0 as outputs
and I/O lines #7, 5, 4, 3, 2, & 1 as inputs.

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