Chino AL3000 SERIES User manual

Please make sure that this manual is handed to the final user of the instrument.
INST.№ INE-272K
COMMUNICATION
INTERFACES
A
L3000/AH3000 SERIES
HYBRID RECORDER
Retain this manual apart from the
instrument and in an easily accessible.

Contents
INTRODUCTION 1
1 GENERAL 2
1.1 RS-232C Communications Interface
1.2 RS-422A/485 Communications Interface
2COMMUNICATIONS PROTOCOL 2
2.1 Communications Protocol and Mode Switching
3 COMMUNICATIONS SPECIFICATIONS 3
4 CHECK AND SETTING OF COMMUNICATIONS PARAMETERS 4
4.1 Check of Communications Parameters
4.2 Programming (Changing) Communications Parameters
5 CONNECTIONS 6
5.1 Connection Precautions
5.2 Communications Cables
5.3 RS-232C Connections
5.4 RS-422A/485 Connections
6MODBUS PROTOCOL 12
6.1 Message Transmission Modes
6.2 Data Time Interval
6.3 Message Configuration
6.4 Creating a Message
6.5 Function Code
6.6 Processing in Abnormal Status
6.7 Title Printing Function
6.8 Data Communication Input
6.9 Table of Reference
7PRIVATE PROTOCOL 62
7.1 Basics of the Communications Sequence
7.2 Control Character Code
7.3 Data Link
7.4 Data Transmission and Reception
7.5 Checksums
8 HARDWARE CHECK FOR COMMUNICATIONS FUNCTION 68
8.1 Connection
8.2 Hardware Check Procedure
9 HOW TO CHANGE THE COMMUNICATIONS PORT 70
10
SAMPLE PROGRAM (For Private Protocol) 71
10.1 Sample Program for RS-232C Communications Interface
10．2 Sample Program for RS-422A /485 Communications Interface

－1－
INTRODUCTION
This instruction manual describes the specifications and operation of three built-in communications
interfaces (RS-232C, RS-422, and RS-485) of the AL3000/AH3000 series Hybrid Recorders.
The explanation for these interfaces are partly the same. However, their differences are explained
separately in [ In case of RS-232C] and [In case of RS-422A and RS-485]. Please read the required part
carefully. Be sure to confirm the model code of the AL3000/AH3000 recorders you purchased as this
determines the required communications interface type.
AL3000 Series Recorders
AL3
AH3000 Series Recorders
AH3
Communications interface
N: None
A: RS-422C
S: RS-485
R: RS-232C
E: Ethernet
Communications interface
N: None
A: RS-422A
S: RS-485
R: RS-232C
E: Ethernet
1. Other Instruction Manual to be consulted.
To understand the contents of this instruction, it is necessary to fully understand the operations and
specifications of the AL3000/AH3000 series recorders.
This instruction manual is for the communications interface only. For the running and operation, please
refer to the following instruction manuals:
1. AL3000 series Hybrid Recorders (Manual No. INE-270)
2. AH3000 series Hybrid Recorder (Manual No. INE-271)
3. AL3000 series (Pen Type) AH3000 series (Pen Type) Hybrid Recorders (Manual No. INE-308)
4. SC8-10 Line Converter (Manual No. INE-39)
※Also refer to the instruction manual of the computer being used.
2.Caution Display
This manual contains explanation of precautions. Observe these precautions when operating and handling
the communications interfaces, otherwise the instrument maybe damaged, resulting in a deterioration in its
performance, or operation failures may also occur.
(1) The right is reserved to change the contents of this manual at any time
without notice.
(2) The contents of this manual have been prepared professionally.
However, if you have any questions, or notice of error or an omission of
descriptions found on this manual, please contact your nearest CHINO
sales agent.
(3) CHINO Corporation is not responsible for any results influenced by the
operation of this communications interface, irrespective of item (2)
above.
Caution

－2－
1GENERAL
There are three types of communication interfaces (RS-232C, RS-422A and RS-485) available between
the AL3000/AH3000 recorders and personal computers (PCs).
PCs can be used to receive measured data from the AL3000/AH3000 recorders, program different
parameters and issue control commands. The number of AL3000/AH3000 recorders that are connectable
to a PC is one for the RS-232C and up to 31 for the RS-422A/485.
1.1 RS-232C Communications Interface
The RS-232C is the data communications standard being set and issued by EIA (Electronic Industries
Association) in the USA and JIS C 6361 in Japan.
This standard is a basic interface between MODEM and connected data terminal units, and specifies
electrical and mechanical specifications only. Most of the RS-232C communications interface is being used
for personal computers and industrial instruments such as AL3000/AH3000 recorders do not completely
conform to this standard at present, and have different signal wire numbers, connectors to those specified in
the standard. Also, since this standard does not specify any software parts, or so-called [data transmission
procedures], units having the RS-232C communications interface can not be interconnected with each
other unconditionally. With these reasons, users must survey and check the specifications and transmission
procedures in advance of units being connected. However, if the counter unit is for a personal computers
or similar device which can optionally program the specifications, then all the units can be combined by
having proper programs prepared by a program designer.
1.2 RS-422A/485 Communications Interface
The RS-422A and RS-485 communications interface can communicate with multiple AL3000/AH3000
recorders (up to 31 sets) in parallel by signals conforming to RS-422A and RS-485.
There are few personal computers which provide RS-422A or RS-485 communications interface. However,
since these communications interfaces are characterized with serial communications, these are easily
connectable to the personal computer having the RS-232C communications interface by using an RS-422A
or RS-485 ⇔RS-232C signal converting unit. A line converter (Model SC8-10: sold separately) is available
for RS-422A and RS-485 ⇔RS-232C signal conversion at CHINO.
Regarding the difference between RS-422A and RS-485 communications interfaces, the RS-422A needs
four signal cables, while RS-485 needs only two signal cables.
2COMMUNICATIONS PROTOCOL
AL3000/AH3000 recorders have the following two communications protocols which can be selected by key
programming.
(1) MODBUS Protocol (MODBUS is the registered trademark of Schneider Automation Inc.)
MODBUS Protocol has RTU mode and ASCII mode which can be selected by key programming.
MODBUS protocol provides the function of transmitting measured data as well as the programming and
operating function.
(2) Private Protocol
This protocol has only the function of transmitting measured data. It is compatible with our products AL56*,
AL.66*, AH5**, AH6** and AH7** recorders.

－3－
2.1 Communications Protocol and Mode Switching
(Note) When switched from ASCII mode to RTU mode, the character configuration is forcibly changed to "8 bits,
parity disabled, stop bit 1".
3COMMUNICATIONS SPECIFICATIONS
* Half-duplex (polling selecting system)
* Protocol: MODBUS protocol/Private protocol
* Transmission speed: 19200, 9600, 4800, 2400, 1200 bps selectable (depending on protocol)
* Start bit: 1 bit
* Data length: 7 bits/8 bits selectable
* Parity bit: Even / Odd / Disabled selectable
* Stop bit: 1 bit / 2 bits selectable
* Transmission code : Binary / ASCII (depending on protocol)
* Error check: Depending on protocol
* External units given priority for communications
* Data transmission procedure: None
* Signals in use: Transmitted and received data only (no control signal in use)
Operation Display
MODBUS
protocol
selected?
Y
ES
NO
PROTOCOL PRIVATE
COMMODE ASCII
IFPORT COM
3 sec. or more, and
＋
(
Note
)
PROTOCOL MODBUS
COMMODE RTU

－4－
4 CHECK AND SETTING OF COMMUNICATIONS PARAMETERS
4.1 Check of Communications Parameters
By pressing + keys for more than 3 sec. under the operation display condition, the
[Communications parameters] check display appears and then program the parameters.
Checking flow chart (Displays shown are default values.)
Communications type
RS-232C, RS-422A or RS-485
Address [instrument number] * 1
(01 to 31 required for RS-422A/485 only.)
Transmission speed * 2
(1200, 2400, 4800, 9600,19200bps)
Character formation * 3
Code
Data length Parity check
Stop bit
7E1 1
7E2 Even 2
701 1
702
7 bits
Odd 2
8N1 1
8N2 Non 2
8E1 1
8E2 Even 2
801 1
802
8 bits
Odd 2
Note) RTU Mode : 8 bits only
Check sum enabled/disabled *4
ON: (enabled) OFF :(disabled).
+
Operation Display
The display of parameters is different by the communications type.
*1: When Private Protocol is selected, the programmable range of address is 01 to 99. The address i
s
automatically programmed to “01” upon switching from Private to MODBUS protocol. There is n
o
change in communications address when changing from MODBUS to Private Protocol.
*2: A selectable bit rate depends on the protocol in use. Bit rate is automatically changed to “9600 bps
”
upon changing from Private to MODBUS protocol. No change in bit rate when changing from
MODBUS to Private Protocol.
*3: Character code is automatically changed to "8N1 (8 bits, parity disabled, stop bit 1)” upon changing
from Private to MODBUS protocol. No change in character code when changing from MODBUS t
o
Private protocol.
*4 : Not displayed when MODBUS protocol is selected.
Not displayed on RS-232C
ADDRESS
BIT RATE
CHARACTER 8N1
For more than 2 sec
CHECK SUM ON
COMMUNI RS-422
A
For more
than 3 sec.

－5－
4.2 Programming (Changing) Communications Parameters
This procedure is used to match the communications
protocols between PCs and AL3000/AH3000 recorders or
program communications addresses (instrument Nos.).
Programming Flow Chart (Displays shown are default values.)
Item Parameters
Protocol MODBUS
Communications Address
01
Transmission Speed
9600bps
Character length
8 bits
Parity Non
Communication s
Character
Stop bit 1 bit
Reference
Default Communications
Parameters
＋
Operation Displa
y
STORE
Programming transmission speed
*2
Select the transmission speed by
key.
(1200, 2400, 4800, 9600 or 19,200)
STORE
STORE
Programming check sum *4
Select ON (enabled) or OFF (disabled
)
by key.
STORE
COMMUNI RS-422A
For shifting the cursor
Programming can b
e
executed when curso
r
a
pp
ears.
BIT RATE
CHARACTER 8N1
CHECK SUM ON
Confirmation of interface type
One of RS-232C/422A/485 on display.
(The interface type specified on ordering
is displayed.)
Starts programming.
For more
than 3 sec.
For more than 2 sec.
The display of parameters is different for each communications type.
Programming communications address
*1
Move cursor and program instrument No.
by to keys.
(Programming range between 01-31)
Not displayed on RS-323C
Programming communications character
*3
Select the code by key.
(*1 to *4: Refer to Para.4.1)

－6－
5CONNECTIONS
5.1 Connection Precautions
5.1.1 Communication Terminals
Disposition of terminals are different with each communications interface.
5.1.2 Total extension of RS-422A/485 communications cable is up to 1.2km.
The wiring interval between each instrument is option, but the total extension distance of cable is within
1.2km.
(Line converter the final end of AL3000/AH3000 recorders)
5.1.3 Noise preventive terminals
Separate the communications cable from drive power cables and other communications cable more than
50cm so as not to be affected by noises.
5.1.4 Crimp style terminals
Falling off of connections is one of communications
failures. Terminate the communications cable with an
[O] or [Y] type crimp style terminal having an
insulation sleeve. (The terminal screws of
AL3000/AH3000 recorders and line converters are
M3.5mm.)
5.1.5 Mount an insulation resistor
For using the RS-422A or RS-485 communications interface, mount a 100 Ωresistor to the
AL3000/AH3000 recorder connected at the final end. (For details, see Section 5.4)
[A general metal film resistor can be used. The resistor (sold separately) is available at CHINO.]
5.1.6 Number of AL3000/AH3000 recorders connectable
For RS-232C: 1 set
For RS-422A or RS-485: Up to 31 sets
Total extension of cable: Within 1.2km
Line converter AL3000/AH3000 recorders
RDA
SDA SDB
RS-422A Terminals
RS-232C Terminals
SD RD SG
RS-485 Terminals
SA
Insulation sleeves
O type crimp terminal
3.7 more
8 or less
3.7 more
8 or less
Y type crimp terminal
Insulation sleeves
(mm)
RS-422A
RDB SG
RS-232C RS-485
SB SG

－7－
5.2 Communications Cables
Make ready cables dedicated to communications before performing connection. Dedicated communications
cables (sold separately) are available at CHINO.
5.2.1 Communications cables for RS-232SC
(1) Connection between PC (with 9 pin-terminal) and AL3000/AH3000 recorder and between PC (with 9
pin-terminal) and line converter.
Cable 9-pin connector RS-232C cable with O-shaped crimp terminal
Style
Internal wiring
Type code
RZ-CRS6
Cable length of 1 to 15 m (To be specified)
(2) Connection between PC (with 25 pin-terminal) and AL3000/AH3000 recorder and between PC(with 25
pin-terminal) and line converter.
Cable 25-pin connector RS-232C cable with O-shaped crimp terminal
Style
Internal wiring
Type code
RZ-CRS2□□
Cable length of 1 to 15 m (To be specified)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
RD
SD
SG
25-pinconnector
to PC
To AL3000/AH3000 recorder
or line converter
In case of NEC's PC98 series(except NX)
SD
RD
SG
SD
RD
SG
1
2
3
4
5
6
7
8
9
RS-232C cable (max. length of 15 m)
RD
SD
SG
9-pin connector
to PC
To AL3000/AH3000
recorder or line converter
RS-232C cable
(
max. len
g
th of 15 m
)

－8－
5.2.2 Communications cables for RS-422A
(1) Connection between line converter and AL3000/AH3000 recorder
Cable
O-shaped crimp terminal RS-422A cable with O-shaped crimp terminal (for line converter)
Style
The cable consists of a pair of twisted dual-core CVVS wires with SG (signal
grounding) wire at both ends. Cut off the SG wire on the line converter side because
this has no SG terminal.
Internal wiring
Type code
RZ-CRA2
Cable length of 1 to 99 m (To be specified)
(2) Connection between AL3000/AH3000 recorder and AL3000/AH3000 recorder
Cable
O-shaped crimp terminal RS-422A cable with O-shaped crimp terminal (for parallel connection)
Style
The cable consists of a pair of twisted dual-core CVVS wires with SG (signal
grounding) wire at both ends.
Internal wiring
Type code
RZ-CRA1
Cable length of 1 to 99 m (To be specified)
RDA
RDA
RDB
RDB
SDA
SDA
SDB
SDB
SG SG
To line converter To AL3000/AH3000 recorder
RDA RDA
RDB RDB
SDA SDA
SDB SDB
SG SG
To AL3000/AH3000 recorde
r
To AL3000/AH3000 recorder
RDB
RD
A
SD
A
SD
B
SG
RDB
RDA
SDA
SDB
SG
RD
B
RD
A
SD
A
SDB
SG
RDB
RDA
SDA
SDB
SG

－9－
5.2.3 Communications cables for RS-485
(1) Connection between line converter and AL3000/AH3000 recorder
Cable
O-shaped crimp terminal RS-485A cable with O-shaped crimp terminal (for line converter)
Style
The cable consists of a twisted dual-core CVVS wires with SG (signal grounding) wire
at both ends. Cut off the SG wire on the line converter side because this has no SG
terminal.
Internal wiring
Type code
RZ-LED (for line converter)
Cable length of 1 to 200 m (To be specified)
(2) Connection between AL3000/AH3000 recorder and AL3000/AH3000 recorder
Cable
O-shaped crimp terminal RS-485 cable with O-shaped crimp terminal (for parallel connection)
Style
The cable consists of a twisted dual-core CVVS wires with SG (signal grounding) wire
at both ends.
Internal wiring
Type code
RZ-LEC (For parallel connection)
Cable length of 1 to 200 m (To be specified)
RD
A
RD
B
SG
SA
SB
SG
To line converter To AL3000/AH3000 recorder
RD
A
RDB
SG
SA
SB
SG
S
A
S
B
SG
SA
SB
SG
To AL3000/AH3000 recorder To AL3000/AH3000 recorder
S
A
SB
SG
SA
SB
SG

－10－
5.3 RS-232C Connections
The AL3000/AH3000 recorders use three control signals of Send(SD), Receive(RD), Signal ground (SG)
only. Since general personal computers are controlled by control signals, the computer does not function by
only connecting three signal cables without wiring processing inside the connectors. Wiring processing
depends upon the control signals being controlled by the personal computer. For details, read the
instruction manual for the personal computer used.
The RS-232C cable length is restricted to be within 15m. The connection for NEC PC98 series
9-pin connector is on [Connection sample 1] and for the 25-pin connector is on [Connection sample 2].
ATTENTION!
[Connection
Exam
p
le 1
]
[Connection
Example 2]
25
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24
SD RD SG
RS
CS
DR
ER
25-pin connector
(PC-98 series)
25
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24
SD
RD SG
RS
CS
DR
ER
CD
25-pin connector
25
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24
SD RD SG
RS
CS DR
ER
CD
25-pin connector
SD RD SG
RS
CS
DR
ER
1 2 3 4 5
6 7 8 9
9-pin connector
(PC-98 series/IBM-PC/AT)
A
L3000/AH3000 recorder
A
L3000/AH3000 recorder
AL3000/AH3000 recorder
A
L3000/AH3000 recorder
[Connection
Example 4]
[Connection
Example 3]
Communications
Cable
RZ-CRS6□□
Communications
Cable
RZ-CRS2□□

－11－
5.4 RS-422A, RS-485 Connections
This paragraph describes the method of connecting the RS-422/485 communications interface to the
personal computer by using the line converter (Model SC8-10: sold separately). Since the line converter
and the personal computer use three control signal of Send, Receive and Signal ground only, the wiring
processing inside the connectors is necessary in the same way as in RS-232C connections.
[For details, read the instruction manual for line converter (Model SC8-10: sold separately).]
RD
SD
SG
RDA
RDB
SDA
SDB
1
2
3
4
5
6
7
8
1 2 3 4 5
6 7 8 9
SDA SDB RDA RDB SG
SDA SDB RDA RDB SG
SDA SDB RDA RDB SG
AL3000/
AH3000
recorder
AL3000/
AH3000
recorder
AL3000/
AH3000
recorder
Line converter
9-pin connector
(The wiring processing inside th
e
connector is necessary.)
9-pin connector
(The wiring processing insid
e
the connector is necessary.)
Termination
resistor 100
AL3000/
AH3000
recorder
AL3000/
AH3000
recorder
AL3000/
AH3000
recorder
1 2 3 4 5
6 7 8 9
SA SB SG
SA SB SG
SA SB SG
Line converter
Termination
resistor 100Ω
In case of RS-422A
In case of RS-485
RD
SD
SG
RDA
RDB
SDA
SDB
1
2
3
4
5
6
7
8
Communications
Cable
RZ-CRA1□□
Communications Cable
RZ-CRA2□□
Communications
Cable
RZ-CRS6□□
Communications
Cable
RZ-LEC□□□
Communications
Cable
RZ-CRS6□□
Communications Cable
RZ-LED□□
Receiving
data
SDA
SDB
Sending
data
RDA
RDB
Inside circuit
SA
SB
Inside circuit
Receiving
data
Sending
data
Please do not connect
SG line to FG terminal
or the protective conductor
terminal of instrument.
Caution!
Please do not connect
SG line to FG terminal
or the protective conductor
terminal of instrument.
Caution!

－12－
6MODBUS PROTOCOL
Basic Procedures of Communications and Precautions
Attention!
1. A data request immediately after turning the power on will lead to an error.
The AL3000/AH3000 series recorders are always ready for communications. They are at anytime
responsive to data requests from personal computers. However, immediately after turning the power on,
the recorders do not deliver a normal response until the data of all channels is ready. It takes, for
instance, about 20 seconds until all the data becomes ready for a 24-point type AH3000 series recorder.
When receiving a data request during this period, the recorders return the error message No.12 (set
mode error).
2. Take care of command re-transmission as there is no control signal line in use.
Since the AL3000-AH3000 series recorders' serial interfaces communicate freely without using any
control line, a reception failure may occur under some conditions. Exercise care when resending a
command.
3. Don't disconnect or short any cables or instruments constituting the serial
interface, or turn the power on or off during communications.
Don't disconnect or short any cables or instruments constituting the serial interface, or turn the power on
or off during communications, or the operation may stop or lead to a malfunction. When this happens, all
the components of the serial interface must be reset to repeat the operation from the beginning.
4. Send the next command after making sure that the communications drive has
been turned off.
For RS422A/RS-485 communications interface, multiple instruments are connected to the same
communications line, only one instrument, of which instrument No. is specified by the PC, drives the
communications line. The communications drive is turned off at a certain time (approx. 5 msec) after
sending the last character so that all the characters are safely received by the personal computer. If the
PC sends a command to the next unit before the communications drive is turned off, signals interfere
with each other resulting in some communication failure. Exercise caution when you use a high-speed
PC.

－13－
6.1 Message Transmission Modes
There are two modes of message transmission, RTU (Remote Terminal Unit) and ASCII, which can be
selected by key programming.
(Table 1 Comparison between RTU and ASCII modes)
Item RTU mode ASCII mode
Interface RS-232C, RS-422A､RS-485
Communications system Half-duplex start-stop synchronization
Transmission speed 9600，19200bps
Character code Binary ASCII
Vertical Parity
Error check Horizontal CRC-16 LRC
Start bit 1 bit
Data bit 8 bits 7 bits, 8 bits (Note)
Parity bit Disabled, even, odd Disabled (Note), odd, even
Character
Configuration
Stop bit 1,2 bit
Message start code None : (Colon)
Message stop code None CR, LF
Data time interval 28 bit-time or less 1 second or less
(Note) 8 bits are also available at AL3000/AH3000 recorders.
(Note) "Parity disabled" is not available when data bits are 7.
6.1.1 Transmitted data
The RTU-mode data is transmitted in binary numbers. In ASCII mode, the 8-bit binary data of RTU is
separated into higher-order 4 bits and lower-order 4 bits and both are turned into characters (0 - 9, A - F).
Example) RTU mode
ASCII mode
67H 36H (“6”)
89H 37H (“7”)
ABH 38H (“8”)
39H (“9”)
41H (“A”)
42H (“B”)
Length of the RTU-mode message is half that of an ASCII-mode message, ensuring a more efficient
transmission.
6.1.2 Message frame configuration
The RTU-mode data consists only of a message section.
The ASCII mode data consists of a start character [ ": (colon, 3AH)], a message and a stop character
[("CR (carriage return, 0DH) + LF (line feed, 0AH) ].
RTU ASCII
Message
：Message CR LF
The ASCII mode has the advantage of easier troubleshooting because its message has a start character
[ : ].

－14－
6.2 Data Time Interval
In RTU mode: Below 28 bit-time (2.8 msec. at 9600 bps, 1.4 msec. at 19200 bps)
In ASCII mode: Below 1 second
When sending a message, keep the time interval of data constituting one message not longer than the
time specified above. When the time interval of data is longer than the above, the receiver unit (i.e., this
recorder) recognizes that the data transmission from the sending unit is complete, so that the subsequent
data is processed as an abnormally received message.
While the message characters must be consecutively sent in RTU mode, the ASCII modes allows for a
maximum interval of 1 second between characters, making it possible to use a master unit (PC) with a
relatively slow processing speed.
6.3 Message Configuration
The MODBUS message has the following configuration in both RTU and ASCII modes.
Slave address
Function code
Data
Error check
6.3.1 Slave address
The slave address can be programmed in advance by key operation within a range between 1 and 31.
The master unit usually communicates with one slave unit. While messages from the master unit are
received commonly by all the units in connection, only the slave unit corresponding to the slave address
included in the command message responds to the message sent.
In case of the RS-232C, send "1" as a slave address. This recorder also sends a slave address of "1".
The slave address "0" is used for a message from the master unit addressed to all the slave units
(broadcast message). The slave units do not send a response back to the master unit.
6.3.2 Function code
Function codes refer to the functions to be executed by the slave units. The data is generally classified as
follows. Refer to the reference table for details.
(1) Digital parameters: Parameters are mainly for changing the functions such as print ON/OFF
and digital data print execution.
(2) Digital input data: Parameters are such as remote contacts input status, input data status and
alarm status.
(3) Analog parameters: Information on various parameters. Numerical values should be kept within
the 16-bit range between -32768 and 32767 (see the reference table for
details). If the data cannot be expressed with 16-bit numbers, use floating
data for reading and writing.
(4) Analog input data: Information on measured data and instrument specifications. Numerical
values within the range of 16-bits are delivered as an output. If the data
cannot be expressed with 16-bit numbers, use floating data (floating-point
data) for reading.
(5) Floating data: If the data cannot be expressed with the numerical values within the 16-bit
range (between –32768 and 32464), use floating data for its expression.
This expression is not available in the standard MODBUS.

－15－
(Table 2. Function code table)
Code Functions Unit
MODBUS original functions (ref.)
01 Read digital (ON/OFF) parameter 1 bit Read coil status
02 Read digital input data 1 bit Read input relay status
03 Read analog parameter 16 bit Read hold register contents
04 Read analog input data 16 bit Read input register contents
05 Write digital parameter 1 bit Change single coil status
06 Write analog parameter 16 bit Write single hold register
08 Send received data (for diagnosis) Loop-back test
16 Write two or more analog parameters
Write into two or more hold registers
70 Read floating data Arbitrary command to vendor
71 Write floating data Arbitrary command to vendor
6.3.3 Data section
Data configurations depend on the function codes. A master request consists of the code number of the
data to be read or written (Relative No. to be calculated from the Reference No. described below) and the
number of data pieces. Response from slave units consists of data responsive to the request.
Every MODBUS basic data consists of 16-bit integers, with or without codes depending on individual data.
It is thus configured as integers with their decimal places assigned to separate addresses, or normalized
with the upper and lower limits specified by the scale with fixed decimal places. The AL3000/AH3000
recorders employ the system of assigning the decimal places to separate addresses. Numerical data that
cannot be expressed with 16-bit integers can be read and written using floating data. Note that floating data
expression is not available in the standard MODBUS.
6.3.4 Reference Nos.
Data in the AL3000/AH3000 recorders have "Reference No." assigned to each of them which is required
for reading and writing the data. The data in the AL3000/AH3000 recorders are classified into "Digital
parameter", "Digital input data", "Analog input data", "Analog parameter" and "Floating (floating-point) data"
depending on their type. The Nos. in the message are designated by the "Relative Nos." corresponding to
the Reference Nos.
(Table 3. Reference Nos. and Relative Nos.)
Data type Reference No. Relative No.
MODBUS original (for reference)
Digital parameter 1 to 10000 Reference No. – 1 Coil
Digital input data 10001 to 20000 Reference No. – 10001 Input relay
Analog input data 30001 to 40000 Reference No. – 30001 Input register
Analog parameter 40001 to 50000 Reference No. – 40001 Hold register
Floating data 50001 to 60000 Reference No. – 50001
Example) Relative No. of Channel 1 data at "Reference No. 30101" is "100.

－16－
(Table 4 Quick search table for Reference Nos.)
Data type Parameters Reference No Corresponding
function code
Reference
table
Digital parameter
Key lock
Message1 printing
Print ON/OFF
Feed
List printing
Title printing
Digital data printing
Temperature unit
High-speed trace printing
Time-axis synchronization
List printing 1 to 3
Alarm relay coil
Alarm output latching
1 to 50 01(READ)
05(WRITE)
Section 6.9.1
（P.29 to 30）
Digital input data
Remote contacts status
(contact input)
Measured data status
Alarm status
10001 to 10500 02(READ) Section 6.9.2
（P.31 to 33）
Analog input data Instrument information
Measured data
30001 to 30050
30101 to 30200 04(READ) Section 6.9.3
(P.33 to 36)
Analog parameter
Programming for all channels
Clock
Chart speed
Periodic data printing
Printing format selection
Zone printing
Alarm deadband
Programming for each channel
Range
Scale
Burnout
Printing color
Subtract printing
Engineering unit
Tag
Alarm
Math
Printing scale
Math parameter
Compressed/expanded
printing
Digital filter
Automatic range–shift
printing
Alarm relay (1 to 18) output
mode
Title printing
Remote contacts function
Message printing
Data communications input
40001 to 40100
40101 to 42500
46301 to 46350
48001 to 48050
48051 to 48100
48201 to 48250
49001 to 49050
03(READ)
06(WRITE)
16(WRITE)
Section 6.9.4
(P.36 to 54)

－17－
Data type Parameters Reference No Corresponding
function code
Reference
table
Floating data
Measured data
Data communications input
Programming for each channel
Range
Scale
Alarm value
Math
Compressed/expanded
printing
Automatic range–shift
printing
50101 to 50150
50201 to 50250
50301 to 51500
70(READ)
71(WRITE)
Section 6.9.5
(P.54 to 61)
6.3.5 Error check
Error check for transmission frames is different between the transmission modes.
RTU mode: CRC-16
ASCII mode: LRC
6.3.5.1 Calculation of CRC-16
In the CRC system, the information to be transmitted is divided by a generating polynomial, the resulting
remainder being added to the end of the data. The generation polynomial is as follows.
1+X
2+ X15 + X16
The data from its slave address to its end is calculated in the following procedure.
1) Initialize the CRC-16 data (assumed as X) (= FFFFH)
2) Exclusive logical sum (EX - OR) between data 1 and X X
3) Shift X one bit to the right X
4) When a carry is generated, take A001H and EX-OR. If not, go to 5). X
5) Repeat 3) and 4) until shifting 8 times.
6) EX-OR between the next data and X X
7) Same as 3) to 5)
8) Repeat up to the last data
9) Create a message in the sequence from lower to upper orders of the calculated 16-bit data (X).
Example) Since CRC-16 is 1241H for the data 01H 07H , the error check data will be 41H 12H.
Reference: CRC-16 Calculation Program
10 D(1) = &H2 : D(2) = &H7 : N = 2
20 GOSUB *CRCMAKE
30 END
40
100 *CRCMAKE
110 CRC = &HFFFF
120 FOR I = 1 TO N
130 CRC = CRC XOR D(I)
140 FOR J = 1 TO 8
150 CY = CRC AND &H1
160 IF CRC < 0 THEN P = &H4000 ELSE
P=0:GOTO180
170 CRC = CRC AND &H7FFF
180 CRC = CRC 2
190 CRC = CRC OR P
200
IF CY = 1 THEN CRC = CRC XOR
&HA001
210 NEXT J
220 NEXT I
230
IF CRC < 0 THEN P = &H80 ELSE
P=0:GOTO250
240 CRC = CRC AND &H7FFF
250 C1 = CRC AND &HFF
260
C2 = ( CRC AND &H7F00 ) 256
270 C2 = C2 OR P
280 D (N+1) = C1 : D(N+2) = C2
290 RETURN

－18－
6.3.5.2 Calculation of LRC
The data from its slave address to its end is calculated in the following procedure.
1) Create a message in RTU mode.
2) Add the start (slave address) to end of the data. -- X
3) Complement X (bit reverse) -- X
4) Add 1 (X = X + 1)
5) Add X as an LRC to the end of the message.
6) Convert the whole data to ASCII characters.
Example) For the data 02H 07H , LRC is F7H which will be 02H 07H E7H as a binary
message,
so that the ASCII message will be 30H 32H 30H 37H 46H 37H .
6.3.6 Precautions on data processing
(1) Since the measured data and decimal places are assigned to separate numbers, it is necessary to use
both parts of the information when playing back the data.
(2) Since data is accessible (changeable) one by one, care must be taken when programming related data,
for instance when initializing related data by changing the range number. Processing details are given
in the Reference No. list.
(3) Programming through communications is not acceptable during programming execution by key
(programming using the key). To avoid this, perform key lock before programming through
communications.
(4) Read or write the data within the range of Reference Nos. specified. If data is written on any Reference
No. not specified, it is likely to affect the proper operation of the instruments.
(5) While it is possible to write data on two or more discreet Reference Nos., a start number with
Reference No. not specified will result in an error (error No. 02H).
(6) When reading two or more Reference Nos., the data with Reference No. not specified becomes "0".
(7) When an error is detected during writing on two or more Reference Nos., all the programming
becomes invalid.
6.4 Creating a Message
A message consists of (1) Slave address, (2) Function code, (3) Data section and (4) Error check code.
(See Section 6.3)
The message readable or writable at one time is within the following range.
Data type Number of data pieces
Floating data 60
Other than floating data 120
How to create a message will be described by an example given below.
Example) Reading a measured data for AL3000/AH3000 recorder Channel 1 with "slave address 02".