AD-4408A
Weighing Indicatorfor Modbus-RTU Interface
AX-ABCC-MODBUS

INSTRUCTION MANUAL

1WMPD4001975

WARNING DEFINITIONS
The warnings described in this manual have the following meanings:
A potentially hazardous situation which, if not avoided, could result indeath or serious injury.
A potentially hazardous situation which, if not avoided, may result inminor or moderate injury or damage to the instrument.
This symbol indicates caution against electrical shock. Do not touch
the part where the symbol is placed.

This symbol indicates the ground terminal.

This symbol indicates that an operation is prohibited.

NOTEInformation or cautions to use the device correctly.

© 2009 A&D Company, Limited. All rights reserved.
No part of this publication may be reproduced, transmitted, transcribed, or translated into any
language in any form by any means without the written permission of A&D Company, Limited.

The contents of this manual and the specifications of the instrument covered by this manual are
subject to change for improvement without notice.
Modbus is a registered trademark of Modicon, Incorporated.
Anybus-CompactCom is a registered trademark of HMS Industrial Networks.
TORX is a registered trademark of Textron Inc.

Contents
1.

Introduction...................................................................................................................22.

Description of Each Part ...............................................................................................3
2.1. Status LEDs ........................................................................................................3
2.2. Communication Connector..................................................................................43.

Installation ....................................................................................................................5
3.1. Interface Module Installation ...............................................................................5
3.2. Connections and Functions.................................................................................6
3.2.1. Cable Connections..........................................................................................6
3.2.2. Setting the Functions ......................................................................................74.

Modbus Memory...........................................................................................................94.1. Memory Map .......................................................................................................94.2. Handling Bits Directly ........................................................................................134.2.1. Handling Command Bits ...............................................................................134.2.2. Command bit execution procedure ...............................................................135.

Timing Chart ...............................................................................................................14

6.

Errors..........................................................................................................................15
6.1. Error Types .......................................................................................................15

7.

Check Mode ...............................................................................................................16
7.1. Checking the Modbus-RTU Communication Status ..........................................16
7.1.1. Entering the Check Mode..............................................................................161

1. Introduction
The AD-4408A functions as a slave device of Modbus (RTU) when the Modbus-RTU
interface module (AX-ABCC-MODBUS) is installed.
A signal level can be selected either for RS-232 or RS-485.
Data communication using Modbus can be performed by pre-mapped memory
operation. Thus, programming communication protocol is not required.

NOTE: Memory map and check modes vary with the interface module installed.
This manual describes performances when the Modbus-RTU interface
module is installed.
When other modules are installed, refer to the relevant instruction manual.
Instruction manuals for each interface module are available on ourwebsite.

22. Description of Each PartNOTE 2

Communication
connector

Locking
catchGround

Lockingcatch

Device status LED

NOTE 1Retainingscrew

Communication LED

Fig.1

Interface module part names

NOTE: 1. A TORX® driver (size T9) to fasten the retaining screws is not provided
with the interface module.
2. A connector for the cable side (D-Sub 9-pin male) is not provided with
the interface module.

2.1.

Status LEDs

NOTE: The illustration below shows how the interface module is positioned wheninstalled to the AD-4408A.

6Device status LED

915Communication LED

Fig.2 Position of status LEDs

Table 1

Device status LED (DS)LED state

Description

OFF

Initializing / No power

Green ONNormal

Red ON

Hardware malfunction

Red, single flash

Communication error / Setting error

Red, double flash

Recoverable error
3

Table 2

Communication LED (COM)LED state

2.2.

Description

OFF

Offline / No power

Yellow ON

Online (Normal)

Red ON

Communication error

Communication Connector

NOTE: The illustration below shows how the interface module is positioned when
installed to the AD-4408A.

69Communicationconnector

15Fig.3 Connector pin assignment

Functions for each pin are as follows.
Table 3

Communication connector

Pin No.

SignalDescription

Housing

SHIELD

1SGSignal ground

25V

Not used

3PMC

Selects the signal level.
RS-232: Connect to pin 2.
RS-485: Leave pin 3 disconnected

4__

5

B (+)

6__

7

RX

RS-232RxD

8TX

RS-232TxD

9A (-)

RS-485A line (Negative side)

Shield (Connected to the AD-4408A FG terminal)__
RS-485

B line (Positive side)__By pin connections, a signal level can be selected either for RS-232 or RS-485.

4

3. Installation
3.1.

Interface Module Installation

Be sure to disconnect the AD-4408A from the power source before
installing the interface module.
Install the interface module as follows:

Blank panel

Step 1 Using a Phillips screwdriver,loosen the screws that secure
the blank panel to theAD-4408A rear panel, andremove the blank panel.

Step 1

Step 2

Step 2 Insert the interface module
into the option slot as shown
to the right.
Step 3 Insert the interface module
until it mates with the terminalsof the PC board connector
located in the option slot.

Option slot
Retaining screw

Interface module
PC boardin the option slot

Step 4 Using a TORX® driver (sizeT9), fasten the retaining
screws with a tightening
torque of 0.25 Nm in theclockwise direction to secure
the interface module.

Step 3Tightening torque0.25 Nm
Step 4Fig.4

Interface module installation

NOTE: A TORX® driver is not provided with the interface module.

53.2 .

Connections and Functions

3.2.1. Cable Connections
By connector pin connections, a signal level can be selected either for RS-232 orRS-485.
When the signal level is RS-485, add a terminator to both ends of the network. Placea terminator between A and B as shown in the figure below.
The A-B terminals of the host device may be reversed, depending on the device
type.
When the host device has no SG terminal, an SG connection is not necessary.
When the cable is to be shielded, connect the cable shield to the connector housing.

Terminator
100-120Ω 1/2W
Host device

AB
SGFG

Some host devices may have aterminator built in.

The A-B terminals of the host device
may be reversed, depending on thedevice type.

AB
SG
Housing (FG)

AD-4408A
No.1

Use a twisted pair cable for a signalline.
Use a shielded cable as necessary.

AB
SG
Housing (FG)

AD-4408A
No.2

AB
SG
Housing (FG)

Place a terminator on thedevice located furthest fromthe host device.

AD-4408A
No.31

Fig.5

Terminator100Ω 1/2W

Example of RS-485 multidrop connection

6

3.2.2. Setting the Functions
The functions described here are general functions.
General functions are divided into groups per function and are indicated by the groupname followed with the function number, FXX.
NOTE: General functions determine the AD-4408A performance and all of thesettings are stored in the FRAM.
Setting Procedure
Step 1 While pressing and holding the ENTER key, press the F key.
fnc is displayed to indicate that the indicator will enter the general functionmode.
Step 2 Press the ENTER key. The indicator enters the general function mode.
To go back to the weighing mode without entering the general function mode,press the ESC key.
Step 3 Press the ∧ or ∨ key to select the function group to be set.
DisplayGroup nameModbus-related functions
rtufPress the ENTER key. The function number will be displayed.
Function No.

Function

Description

Default value

rtuf01

Station No.

1rtuf02

Baud rate

rtuf03

Parity1 to 247: Station No.
1: 1200 bps
2: 2400 bps
3: 4800 bps
4: 9600 bps
5: 19200 bps
6: 38400 bps
7: 57600 bps
8: 76800 bps
9: 115200 bps
0: None1: Odd2: Even

5

2

NOTE: Data bits are fixed to 8 bits and stop bit is fixed to 1 bit.
Step 4 Press the ∧ or ∨ key to select the function number to be set.
Press the ENTER key. The current setting value will be displayed.

7Step 5 Change the setting value using either one of the methods below.
MethodSelecting a parameter

Inputting the value

Description
Only the parameter number to be selected isdisplayed and blinks.
Press the ∧ or ∨ key to select a parameter.
All the digits are displayed and a digit to be changed
blinks.
Press the < or > key to select a digit andpress the ∧ or ∨ key to change the value.

After setting, press the ENTER key. The next function number is displayed.
When the parameter is not to be changed, press the ESC key to return to thefunction number display.
Step 6 Press the ESC key. The function number disappears and the indicator returns tothe state of step 3.
Press the ESC key to store the setting values in the FRAM and go back to theweighing mode.
NOTE: The blinking decimal point indicates that the current value is not the weightvalue.
If a value exceeding the settable range is entered, err dt is displayed andthe input is canceled.

84. Modbus Memory
4.1.

Memory Map

Modbus uses reference numbers and addresses to control the AD-4408A or to read data.
The AD-4408A uses Holding Registers and Input Registers.
Data types and reference numbers are as shown below.
Table 4

Data type

Data types

ReferenceNo.

Description

Read and write bit data
Output Coil0
Corresponds to the input of the control I/O.
Not used for the AD-4408A.
Read only bit data
Input Status
1
Corresponds to the output of the control I/O.
Not used for the AD-4408A.
Read only Word data
Input Register
3
Used to read weight values and command responses.
Read and write Word data
Holding Register
4
Used to send commands.
NOTE: Do not access the memory area that the AD-4408A is not using.

Table 5

Holding Register memory map

Holding Register (Read and write Word data Reference No. 4)
Zero
Clear the zero value
Tare
Clear the tare value
Error reset
Hold*
Manual print command
Net display
Gross display

Bits 9-15 areinternally reserved.
Bit 15 14 13 12 11 10First wordof Holding Register

987654Command bits

*Hold at the rising edge, release at the falling edge
93

210

Table 6Input Register (Read only Word dataBit
First wordof Input Register

Input Register memory map

Reference No. 3)

15 14 13 1211 109 8 76 5 43 2 10UnitDecimal point position

Setting value

Setting value

Unit

Decimal point position
0: None 123456
1: 10112345.6
2
2: 101234.56
3
3: 10123.456
4: 10412.3456
5
5: 10
1.23456

0: None
1: g
2: kg
3: t
4: lb (USA version)

Net overNet under
Gross over
Gross under
Input (A/D) over
Input (A/D) under
Reserved internally
Reserved internally
Checksum error
Input (A/D) error
FRAM error
Calibration error
Mode error
Zero error
Tare error
Net display error
Bit 15 14 13 12 11 10
Second wordof Input Register987Status bits

106543210

Zero
Clear the zero value
Tare
Clear the tare value
Error reset
Hold*
Manual print command
Net display
Gross display

Bits 9-15 areinternally reserved.
Bit 15 14 13 12 11 10
Third wordof Input Register

9876543210

10Command response*Hold at the rising edge, release at the falling edge

Slave normal operation
Slave readyError status flag
StableNet center of zero
Gross center of zero
Capacity exceeded
Tare in progress
Net display
Gross display
Hold in progress
In sync withWeighing failure
Reserved internallyReserved internally
Reserved internallyBit 15 14 13 12 11 10
Fourth wordof Input Register987

Status bits

1165432

Bit
Fifth wordof Input Register

Bit
Sixth wordof Input Register
Bit
Seventh wordof Input Register
Bit
Eighth wordof Input Register
Bit
Ninth wordof Input Register
Bit
Tenth wordof Input Register

15 14 13 1211 10

9 8 7

6 5 4

3 2 103 2 103 2 103 2 103 2 103 2 10

Net weight
Weight value (Low order word)

15 14 13 1211 10

9 8 7

6 5 4

Net weight
Weight value (High order word)
15 14 13 12

11 10

9 8 7

6 5 4

Gross weight
Weight value (Low order word)
15 14 13 12

11 10

9 8 7

6 5 4

Gross weight
Weight value (High order word)
15 14 13 12

11 10

9 8 7

6 5 4

Tare
Weight value (Low order word)
15 14 13 12

11 10

9 8 7

6 5 4

Tare
Weight value (High order word)

12

4.2.

Handling Bits Directly

4.2.1. Handling Command Bits
A command bit is in the first word of the Holding Register.
A command response is in the third word of the Input Register.
To execute, turn the corresponding command bit ON.
The command bit will be effective at the rising edge.
The signal level must be maintained for 30 msec minimum.
Table 7First word of Holding Registerandthird word of Input Register

Command bits

Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8

Command bit and action
Zero
Clear the zero value
Tare
Clear the tare value
Error reset
Hold
Manual print command
Net display
Gross display

4.2.2. Command bit execution procedure
Step 1 The master device turns OFF all the command bits.
Step 2 The master device turns ON the command bit to be executed.
Step 3 The AD-4408A executes the command and turns ON the corresponding
command response.
Step 4 The master device confirms the command response and turns OFF all thecommand bits.

135. Timing Chart
Slave Normal Operation
Slave normal operation is a signal to confirm that the AD-4408A is connected to the power
and is in normal operating conditions. During normal operation, the signal is reversed at a
0.5 to 1 second interval.
Slave normal operation

0.5 to 1 sec

Fig.6

Slave normal operation signal

Error status flag
If an AD-4408A error has occurred, the slave ready bit will be turned OFF and the error
status flag will be turned ON to convey to the master device that an error has occurred.
The master device will turn the error reset flag ON to request resetting the error statusflag.
Error status flag
Error reset flag
Slave readyFig.7
Table 8Resetting the error status flag

Command bits / Status bits

MemoryFirst word of Holding Register
Fourth word of Input Register

Description
Bit 4

Error reset flag

Bit 0

Slave normal operation

Bit 1

Slave readyBit 2

Error status flag

14

6. Errors
6.1.

Error TypesError Status Flag
This conveys to the master device that an error has occurred.
Turn the error reset flag ON to request resetting the error status flag.
Table 9Error status flag

Error type

CausesChecksum error

Program checksum does not match.

Input (A/D) error

Data can not be acquired from the A/D converter.

FRAM error

Data can not be written into the FRAM.

Calibration error

Calibration data is not correct.

Mode error

Moved to a mode other than the weighing mode.

Weighing FailureThis conveys a weighing failure to the master device.
This will be reset when normal weighing has resumed.
Table 10Weighing failure

Error type

CausesZero error

Zero adjustment is not performed.

Tare error

Tare is not performed.

Net display error

A net value is not displayed.

Capacity exceeded

The weighing capacity has been exceeded.

Capacity ExceededThis conveys to the master device that the weighing capacity has been exceeded.
This will be reset when all the errors are cleared.
Table 11

Capacity exceeded

Error type

CausesNet overThe net weight is over the net weight range.

Net under

The net weight is below the net weight range.

Gross overThe gross weight is over the gross weight range.

Gross under

The gross weight is below the gross weight range.

A/D overA/D value is over the A/D value range.

A/D under

A/D value is below the A/D value range.

15

7. Check Mode
7.1.

Checking the Modbus-RTU Communication Status

7.1.1. Entering the Check Mode
Step 1 While pressing and holding the ENTER key, press the F key.
fnc is displayed to indicate that the indicator will enter the general functionmode.
To go back to the weighing mode, press the ESC key.
Step 2 While pressing and holding the ZERO key, press the ENTER key.
1Chc is displayed to indicate that the indicator will enter the check mode.
Press the ENTER key again to display an item to be checked.
Step 3 Press the ∧ or ∨ key to select Chcrtu (Modbus check mode) and press theENTER key to enter the Modbus check mode.
To exit from the check mode, press the ESC key.
Table 12Check mode list

Display

ChckeyChc ClChc∗∗∗
ChcrtuChc∗∗∗
Chc r5
Chc adChc inChcpr9Chc 5nC5 pr9C5 fraCalfdt

Checking item
Key switches
Standard serial output
Interfaces
Modbus-RTU
Testing terminal
A/D (Load cell)
Internal countProgram version
Serial number
Program checksum
Memory (FRAM) checksum
Calibration-related functions16

Checking the Communication Status
Press the ∧ or ∨ key to change addresses.

Two digits: address (01, 11 to 1A)
Four digits: data (0000 to FFFF)

８ ８.８ ８ ８ ８□ □ □ □ □ □Slave error
Slave readyブデ
Slave normal
operation
Interface error
Interface waitInterface active
Address

Data type

Word01

Holding Register

111 to 1A

Input Register

1 to 1017

MEMO18

MEMO

19

MEMO

20