B&B Electronics RS-485 User Manual 2

RS-485 Data Acquisition Module

Model 485SDA10

Document No. 485SDA103798

This product

Designed and Manufactured

In Ottawa, Illinois

USA

of domestic and imported parts by

B&B Electronics Mfg. Co. Inc.

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

PH [phone] -- FAX [phone]

Internet:

http://www.bb-elec.com

[e-mail]

[e-mail]

 1995 B&B Electronics -- Revised September 1998

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Table of Contents

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

485SDA10 Features......................................................1

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

Software Installation......................................................2

DOS...................................................................................... 2

Windows 3.11....................................................................... 3

Windows 9x and Windows NT.............................................. 3

Uninstall.........................................................................3

Windows 3.11....................................................................... 3

Windows 9x & Windows NT................................................. 3

Getting Started..............................................................3

485SDA10 Specifications..............................................5

Analog to Digital Converter................................................... 5

5 Volt Reference................................................................... 5

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

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

Power Supply........................................................................5

Communications...................................................................5

Factory Default Settings .......................................................5

Chapter 2 - Connections..........................................6

A/D Connections............................................................6

A/D Inputs #0-10...................................................................6

A/D Ref Input +..................................................................... 6

A/D Ref Input -...................................................................... 7

Analog Ground...................................................................... 7

Typical Connections .............................................................7

Digital I/O Connections..................................................8

Digital Inputs #0-2.................................................................8

Digital Outputs #0-2.............................................................. 8

Digital Ground.......................................................................9

Typical Connections .............................................................9

Serial Port Connections............................................... 10

Power Supply Connections..........................................11

Chapter 3 - Commands..........................................12

Syntax .........................................................................13

Reading A/D Channels Command...............................13

Reading Digital I/O Command.....................................15

Set Digital Output Command....................................... 16

Set Module Address Command................................... 16

Set Power-up States Command ..................................17

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Set Turn-around Delay Command............................... 17

Read Module Configuration Command........................17

Chapter 4 - A/D .......................................................19

Sampling Rate.............................................................19

A/D Input Range..........................................................19

Reference Inputs.........................................................19

Data Range.................................................................20

Converting Data...........................................................20

Chapter 5 - Software..............................................22

Read A/D Command ...................................................22

Read Digital I/O Command..........................................23

Set Digital Output States ............................................. 24

Set Module Address ....................................................25

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

Set Turn-around Delay ................................................27

Read Module Configuration.........................................28

Appendix A: Adding Data Field Confirmation.... A-1

Appendix B: Analog Input Impedance................B-1

Appendix C: Decimal to HEX to ASCII Table ....C-1

Figures

FIGURE 1.1 - 485SDA10 UNIT...................................................................... 1

FIGURE 1.2 - GENERAL BLOCK DIAGRAM............................................... 2

FIGURE 1.3 - A/D WITH VARIABLE RESISTOR......................................... 4

FIGURE 2.1 - TYPICAL 0-5V A/D CONNECTION ....................................... 7

FIGURE 2.2 - TYPICAL DIGITAL I/O CONNECTIONS............................... 9

FIGURE 4.1 - A/D CONVERTER DATA RANGE........................................ 20

FIGURE B-1 - EQUIVALENT INPUT CIRCUIT INCL/DRIVING SOURCEB-3

Tables

TABLE 2.1 - 485SDA10 I/O PORT PINOUT...................................... 8

TABLE 2.2 - RS-485 TERMINAL BLOCK CONNECTIONS..........10

TABLE 3.1 - 485SDA10 COMMANDS............................................. 12

TABLE 3.2 - EQUIVALENT VALUES.............................................13

TABLE 3.3 - READ A/D RESPONSE................................................ 14

TABLE 3.4 - READ DIGITAL I/O RESPONSE FOR OUTPUTS..... 15

TABLE 3.5 - READ DIGITAL I/O RESPONSE FOR INPUTS......... 15

TABLE 3.6 - SET DIGITAL OUTPUT DATA BYTE VALUES......16

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TABLE 5.1 - DIGITAL I/O MASK VALUES....................................24

TABLE A-1 EXTENDED COMMANDS........................................A-2

TABLE C-1: DECIMAL TO HEX TO ASCII TABLE.................... C-1

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Chapter 1- Introduction

485SDA10 Features

The 485SDA10 is a general purpose control module which
operates through an RS-485 interface. The 485SDA10 offers 11
channels of 10-bit A/D (analog to digital), 3 digital inputs and 3 digital
outputs. With these features, the module can be used to sense a
variety of external conditions and to control a variety of devices.

The 11 A/D channels allow you to measure voltages from 0 to 5
Volts. The 3 digital inputs and 3 digital outputs are CMOS/TTL
compatible. The A/D and digital I/O lines are available through a DB­25S (female) connector.

The 485SDA10 connects to the host computer’s RS-485 or
RS-422 serial port using terminal blocks. The address and turn­around delays are software programmable to allow use of multiple
devices or connection to existing 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.
The configuration parameters consist of the module address,
communication turn-around delay, and digital output power-up
states.

Figure 1.1 - 485SDA10 Unit

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Figure 1.2 - General Block Diagram

Packing List

Examine the shipping carton and contents for physical damage.

The following items should be in the shipping carton:

• 485SDA10 unit

• One 485SDA10 3.5” disk

• This instruction manual

• RS-485/422 Application Note

If any of these items are damaged or missing contact B&B
Electronics immediately.

Software Installation

The 485SDA10 comes with several useful programs such as a
data logging utility, a demonstration program, etc. The installation
for the SDA Logger is different depending on the platform you install
it to. Please use the one appropriate to your system.

DOS

1. Place the disk in drive A.

2. Type A: and press the <ENTER> key.

3. Type INSTALL and press the <ENTER> key.

4. Follow the instructions given by the program.

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Windows 3.11

1. Insert SDA Logger installation disk in your floppy drive.

2. Click the File Manager button.

3. Select the floppy drive containing the SDA Logger
installation disk.

4. Double click the Setup.exe icon when it appears.

5. Follow the installation instructions as prompted.

Windows 9x and Windows NT

1. Insert the SDA Logger installation disk in your floppy drive.

2. Click Start | Run.

3. Click the Browse button and choose the floppy drive
containing the SDA Logger installation disk.

4. Double click the Setup.exe icon when it appears.

5. Click the OK button to run the Setup.exe program.

6. Follow the installation instructions as prompted.

Uninstall

Uninstall for the SDA Logger version is different for each
Windows operating system. Below are the methods for uninstalling
the SDA Logger.

Windows 3.11

1. Open the File Manager in the Control Panel.

2. Click the drive that SDA Logger was installed to.

3. Click the SDA16 directory.

4. Double click the UNWISE.EXE.

5. Follow the Uninstall Wizard.

Windows 9x & Windows NT

1. Open Start | Settings | Control Panel.

2. Open ADD/REMOVE PROGRAMS.

3. Click SDA LOGGER.

4. Click the Add/Remove button.

5. Follow the Uninstall Wizard.

Getting Started

This section will provide a quick example using the 485SDA10
and the demonstration program. If you experience any problems,
refer to Chapter 2 for more precise information on connections. The
demo program continually reads the A/D inputs and the digital I/O.
The states of the digital outputs can be toggled using F2, F3, and
F4. The serial port is configured for 9600 baud, 8 data bits, no
parity, and 1 stop bit. The program supports standard addresses
and IRQ’s for COM1 and COM2.

• Connect a 0 to 5V DC analog device to A/D input #0, or you
can connect a variable resistor as shown in Figure 1.3. The

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variable resistor must be greater than 1k Ohms to limit the
output current to 5mA.

• Connect A/D Ref Input+ to +5V DC.

• Connect A/D Ref Input- to analog ground (See Figure 1.3).

• Connect the 485SDA10 to an RS-422 or 4-wire RS-485 serial

port.

Once your connections have been made, run the demo program.
Any change in A/D or digital lines on the 485SDA10 will
automatically be displayed on the screen.

Figure 1.3 - A/D with Variable Resistor

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485SDA10 Specifications

Analog to Digital Converter
Resolution: 10 bit

Channels: 11

Reference Range: 5.0V DC max. (4.888 mV per bit)

2.5V DC min. (2.444 mV per bit)
A/D Ref. Input - 0V DC to 2.5V DC
A/D Ref. Input + 2.5V DC to 5.0V DC
Input Voltage Range: -0.3V DC to 5.3V DC
Total Unadjusted Error: +/- 1 LSB max.

A/D input channels must be driven from a source impedance less
than 1kΩ.

5 Volt Reference
Output Voltage: 4.975 to 5.025V DC (5.0V DC typ.)

Accuracy: +/- 0.5 %
Output Current: 5mA max.

Digital Inputs
Channels: 3

Voltage Range: -30V DC to 30V DC
Low Voltage: -30V DC to 1.0V DC
High Voltage: 2.0V DC to 30V DC
Leakage Current: 1 µA max.

Digital Outputs
Channels: 3

Low Voltage: 0.6V DC @ 8.7mA
High Voltage: 4.3V DC @ -5.4mA

Power Supply
Input Voltage: 7V DC to 18V DC @ 30mA

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

Communications
Standard: RS-422/485

Addresses: 256

Turn-around Delay: Software programmable from 0 to 255

character transmission times. (1 char.

trans. time @ 9600 baud = 1ms)
Baud Rate: 1200 to 9600 (automatic detection)
Format: 8 data bits, 1 stop bit, no parity

Connector: DB-25S (female)

Factory Default Settings

Address: ACSII “0” (48 decimal or 30h)
Turn-around Delay: 1
Power-up States: 0

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Chapter 2 - Connections

This chapter will cover the connections required for the

485SDA10. There are four sets of connections:

• A/D converter

• Digital I/O

• Serial port

• Power supply

Do not make any connections to the 485SDA10 until you have read
this chapter.
CAUTION: When making electrical connections it is important to
power down the devices being connected. If this is not possible,
precautions must be taken to ensure electrical specifications are not
exceeded.
NOTE: If you do not intend to use a section (A/D or I/O), it is still
important to read each one.

A/D Connections

The A/D connections are made on the I/O port, which is a DB­25S (female) connector. Table 2.1 shows the pinout of the I/O port.
The next sections explain the functions and connections for the
various analog signals.

A/D Inputs #0-10

These are the analog input channels. The analog data that is
read from the 485SDA10 is related to the voltage on these pins.
Connect your devices to the analog input channels. Voltages on
these inputs must remain between 0 and 5.0V DC. Connect unused
A/D inputs to analog ground.

A/D Ref Input +

The voltage connected to this pin determines the upper end of
the input voltage range. For proper operation, this pin must be
connected to a DC voltage between +2.5 and +5.0 Volts. The
485SDA10 provides a 5.0V +/-0.5% reference on pin 17. The 5V
reference can be used if you require a 0 to 5V DC input range. If
your application requires a better reference voltage or a different
input range, you must supply the appropriate reference to the
A/D Ref Input+ pin. This voltage must be at least 2.5V greater
than A/D Ref Input-. Bypassing the A/D Ref Input+ pin with 0.01µF
ceramic and 10µF tantalum capacitors to analog ground will
decrease noise levels.

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A/D Ref Input -

The voltage connected to this pin determines the low end of the
input voltage range. For proper operation, this pin must be
connected to a DC voltage between 0 and +2.5 Volts. Typically, this
is connected to your device’s ground and analog ground (0V).

Analog Ground

This pin should be connected to your analog device’s ground. If
ground (0V) is the low end of your input voltage range,
A/D Ref Input- should be connected to this pin. To minimize noise,
do not connect analog ground and digital ground together. Connect
unused A/D inputs to analog ground.

Typical Connections

Figure 2.1 shows the typical connections of the 485SDA10 for a
0 to 5V DC input range.

Figure 2.1 - Typical 0-5V A/D Connection

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Digital I/O Connections

The digital I/O connections are made on the I/O port, which is a
DB-25S (female) connector. Table 2.1 shows the pinout of the I/O
port. The next sections explain the functions and connections for
the various digital signals.

Table 2.1 - 485SDA10 I/O Port Pinout

DB-25S

Pin # Function

1 GND 14 Digital Output #0
2 +12V DC Output* 15 Digital Output #1
3 Digital Input #0 16 Digital Output #2
4 Digital Input #1 17 +5V DC Output
5 Digital Input #2 18 A/D Ref. Input +
6 Digital GND 19 A/D Ref. Input ­7 Analog GND 20 No connection
8 A/D Input #0 21 A/D Input #6

9 A/D Input #1 22 A/D Input #7
10 A/D Input #2 23 A/D Input #8
11 A/D Input #3 24 A/D Input #9
12 A/D Input #4 25 A/D Input #10
13 A/D Input #5

*Actual output is equal to power supply input minus 0.7V DC

DB-25S

Pin # Function

Digital Inputs #0-2

The digital input lines are CMOS/TTL compatible and can handle
voltages from -30V DC to +30V DC. If a digital input is from -30V
DC to 1.0V DC, the state will be read as a “0” (LOW). If a digital
input is from 2.0V DC to 30V DC, the state will be read as a “1”
(HIGH). Connect unused digital inputs to digital ground.

Digital Outputs #0-2

The digital output lines are CMOS/TTL compatible. A digital
output that is set to a “0” (LOW) will output a voltage from 0 to 0.6V
DC. A digital output that is set to a “1” (HIGH) will output a voltage
from 4.3V DC to 5.0V DC. Refer to Chapter 1, Specifications, for
more information. Unused digital output lines should be left open.

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