YOKOGAWA 800 plus Use and care manual

Modbus Protocol
COMMUNICATIONS MANUAL
800Plus
Universal Digital Panel Meters, Counters,
Timers and Transmitters, Series 2
No ith Ethernet
2 Dart Rd, Ne nan, GA 30265, USA
Phone: [phone], Fax: [phone]
http:// .yca.com

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1. TABLE OF CONTENTS
1. TABLE OF CONTENTS ....................................................................................................... 2
2. INTRODUCTION, MODBUS PROTOCOL ............................................................................ 3
3. MODBUS CONNECTION EXAMPLES ................................................................................. 4
4. JUMPER SETTINGS & FIELD WIRING .............................................................................. 5
5. PROGRAMMING YOUR MODBUS DEVICE ........................................................................
6. MODBUS PROTOCOL IMPLEMENTATION ........................................................................ 10
1. General .................................................................................................................. 10
2. Framing .................................................................................................................. 10
3. Electrical Interface ................................................................................................. 11
4. Parameters Selectable via Instrument Setup (IS) Software ................................... 11
5. Parameters Selectable via Front Panel Meter Setup ............................................... 11
6. Supported Function Codes .................................................................................... 11
7. Register Numbers vs. Meter Addresses ................................................................. 11
8. Supported Exception Response Codes .................................................................. 14
. Message Formatting .............................................................................................. 14
10. Message Examples for Device Address= 01, No Parity .......................................... 15
11. Data Types Internal Registers ................................................................................ 16
12. DPM & Analog Input Transmitter Internal Register Addresses ............................. 17
13. Counter / Timer Internal Register Addresses ......................................................... 23
7. WARRANTY ...................................................................................................................... 32

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2. INTRODUCTION, MODBUS PROTOCOL
The Modbus Protocol is an industry-standard communications protocol that is selectable with all
our serial communications signal options: Ethernet, USB, RS485 and RS232. It is implemented by
the microcomputer on the main board and is compliant with Modbus RTU or ASCII transmission
modes (software selectable), as specified in Modbus over Serial Line Specification V1.0 (2002).
Digital panel meters, counters and timers require a plug-in option board for Modbus communi-
cations. This board can be any of the following:
• RS232 board
• RS485 board with dual RJ11 jacks.
• RS485 Modbus board with dual RJ45 jacks
• USB board
• USB-to-RS485 converter board
• Ethernet board
• Ethernet-to-RS485 converter board
Our RS485 and Modbus RS485 boards are both Modbus compliant, but the RS485 board uses
RJ11 jacks while the Modbus board uses RJ45 jacks as recommended in the Modbus Specifi-
cation. With either board, the two jacks are wired in parallel to allow daisy chaining of meters with
no need for a hub.
Our USB to RS485 and Ethernet to RS485 converter boards allow the host meter to function as a
normal meter, be connected to a host computer or Ethernet local area network (LAN), and also act
as the device server for an RS485 network with up to 31 other meters equipped with an RS485
board. These meters can then be daisy-chained using readily available, straight-through 6-wire
data cables (not 4-wire telephone cables or crossover cables). Use repeaters to increase the
number of addressable meters.
Our DIN rail transmitters come with a user-selectable Ethernet or RS232/RS485 I/O port in addi-
tion to a scalable 4-20 mA output, which is standard.
Our DIN rail Ethernet to RS485 device server provides an RJ45 jack for connection to the
Ethernet, an RJ11 jack to support an RS485 network of meters, plus screw terminals to support
an RS485 network of DIN-rail transmitters via a set of 3 or 5 parallel wires (half- or full-duplex).
The Modbus TCP
The Modbus TCPThe Modbus TCP
The Modbus TCP protocol is seamlessly converted by our Ethernet Nodes to Modbus RTU or
Modbus ASCII for communication with meters and transmitters on an RS485 bus. Please see our
Ethernet Manual for more information.
The Custom ASCII Protocol is a software-selectable alternative to the Modbus Protocol. It also
allows device addressing of up to 31 devices. It is less complex than the Modbus protocol, but is
limited to use with our devices. Please see our Custom ASCII Protocol Communications Manual.

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3. MODBUS CONNECTION EXAMPLESS

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4. JUMPER SETTINGS & FIELD WIRING
1. SAFETY WARNINGS
Digital panel meters, counters, timers and transmitters may be powered with AC (mains) from
85-264 Vac or 5-300 Vdc with standard high voltage power, or 12-34V ac or 10-48 Vdc with the
low voltage power supply option. To avoid the possibility of electrical shock or damaging short
circuits, always unplug the device before opening the case. Please refer to the respective device
manuals for full safety information and instruction on how to open the case. Signal wiring changes
external to the case can be made safely while the units are under power.
2. JUMPERS ON SERIAL METER BOARDS

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USB Board &
Basic Ethernet Board
No jumpers needed.
RS232 Board
e - Normal operation.
f - Slave display to RS232 from another meter.
g - Pull-up resistor on RTS line.
Note: Board is shipped ith jumpers e and g installed
RS485-Modbus Board, Full Duplex Operation
b & e - Bias jumpers should be installed on 1 board.
a & d - Installed on last meter in long cable run.
RS485-Modbus Board, Half Duplex Operation
b & e - bias jumpers installed on 1 board.
c & f - installed for half duplex operation.
a - installed on last meter in line ith long cable runs.
Note: Board is shipped ith no jumpers installed.
Modbus
b
a
cd e
RJ45
RJ45
f
RS485 Board, Full Duplex Operation
b & d - Installed on last meter in long cable run.
RS485 Board, Half Duplex Operation
a & c - Installed for half duplex operation.
d - Installed on last meter in line ith long cable runs.
Note: Board is shipped ith no jumpers installed.
Ethernet-to-RS485 Converter Board
& USB-to-RS485 Converter Board
Full Duplex Operation
No jumpers for short cable runs.
Add b & d for long cable runs.
Half Duplex Operation
a & c for short cable runs.
d - Installed on last meter in line ith long cable runs.
3. CONNECTOR WIRING, SERIAL BOARD TO COMPUTER

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N/C
ISO GND
RX
TX
RTS
N/C
GND
TX
RX
RTS
RS232 INTERFACE Computer
6
5
4
3
2
1
ISO GND
BRX
ARX
ATX
BTX
ISO GND
GND
BTX
ATX
ARX
BRX
GND
RS485 INTERFACE - FULL DUPLEX
GND
ATX / ARX
BTX / BRX
GND
RS485 INTERFACE - HALF DUPLEX
1
2
3
4
5
6
7
8
(A') RXD0 -
(B') RXD1 +
(B) TXD1 *
(A) TXD0 -
ISO GND
TXD0
TXD1
RXD1
RXD0
GND
RS485-MODBUS - FULL DUPLEX RS485-MODBUS - HALF DUPLEX
(B) TX / RXD1
(A) TX / RXD0
ISO GND
(B) TX/RXD1
(A) TX/RXD0
GND
6
5
4
3
2
1
6
5
4
3
2
1
ISO GND
ATX / ARX
BTX / BRX
ISO GND
1
2
3
4
5
6
7
8
4. TRANSMITTER CONNECTOR WIRING
Signal
conditioner
board
P3 Solid
state relays P1 Po er
input
P6 Signal
input &
excitation
output
P2 Serial
data I/O
P4 Analog
output
1
2
3
4
5
6 RS485 RS232
6 N/C TX
5 ARX RX
4 ATX NC
3 GND GND
2 BRX GND
1 BTX N/C
3 Po er GND
2 AC neutral or -DC
1 AC high or +DC
See belo
for different
signal types
Analog out - 1
Analog out + 2
AL2 1
AL2 2
AL1 3
AL1 4
5
4
3
2
1
9
8
7
6
RS232 cable ith
rear vie of DB9
connector to PC

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E1
E4 E6
E3
E2
a
b
c ab
ab
cd
a
b
c
d
Serial Signal
Duplex
Jumpers
Termination Resistor*
RS485 Full None E6 a = Transmit
E6 c = Receive
Half E6 b + d** E6 c
RS232 Full None None
Serial Signal
Duplex
Jumpers
Termination Resistor*
RS485 Full None E6 a = Transmit
E6 c = Receive
Half E6 b + d** E6 c
RS232 Full None None
* The termination resistor jumper settings should only be selected if the transmitter is the last
device on an RS485 line longer than 200 feet (60 m).
** Attempting to draw more than the rated current will shut down the output.
To reset communications to 600 baud, command mode, Custom ASCII protocol, and Address 1,
place a jumper at E1 and power up the transmitter.
Analog Output
Jumpers
Current E2 a + d
Voltage E2 b + c
Excitation Output*
Jumpers
5V, 100 mA E3 a + c; E4 a
10V, 120 mA E3 a + c; E4 b
24V, 50 mA E3 b, E4 none
* The termination resistor jumper
settings should only be selected
if the transmitter is the last device
on an RS485 line longer than 200
feet (60 m).
** Or jumper external BTX to BRX
and ATX to ARX (same effect as
internal jumpers).

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5. PROGRAMMING YOUR MODBUS DEVICE
OVERVIEW
Modbus digital panel meters, counters, timers and transmitters are easily programmed via their
serial port using Windows-based Instrument Setup (IS) software, which provides a graphical
user interface and is available at no charge. This software allows uploading, editing, down-
loading and saving of setup data, execution of commands under computer control, listing,
plotting and graphing of data, and computer prompted calibration. Digital panel meters,
counters and timers can also be programmed via their 4-key front panel as explained in their
respective manuals; however, online programming is easier. For Ethernet, please see our
separate Ethernet Manual.
GETTING STARTED WITH INSTRUMENT SETUP SOFTWARE
To install IS software, download the file instrument.exe from our website, double-click on the
file name to extract three files, double-click on setup.exe, and follow the prompts. To launch IS
software, press Start => Programs => IS2 => IS2. Establish communications by selecting
matching settings between the instrument and PC, and click on Establish. Once communica-
tions have been established, click on Main Menu.
The best way to learn IS software is to experiment with it. From the Main Menu, click on Get
Setup to retrieve (or get) the existing setup data from your device. Click on View = > Setup to
bring up screens which allow you to edit the setup file using pull-down menus and other
selection tools. You can save your file to disk by clicking on File = > Save Setup. You can
download (or put) your edited file into the device by clicking on Put Setup. Programmable
items will only be displayed if the appropriate hardware has been detected, such as the dual
relay option for meters. Pressing the F1 key at any time will bring up detailed help information.
An analog output is defined in two steps. The input to the device is first scaled to a digital
reading in engineering units, and this reading is then scaled to the analog output. The digital
reading is also used for setpoint control and can be transmitted as serial data.
ADDITIONAL FEATURES
• The Commands pull down menu allows you to execute certain functions by using your
computer mouse. The Comman s pull-down menu will be grayed out unless a Get Setup has
been executed.
• The Readings pull down menu provides three formats to display input data on your PC
monitor. In all formats, use the Pause and Continue buttons to control the timing of data
collection, then press Print for a hardcopy on your PC printer. List presents the latest digital
readings in a 20-row by 10-column table. Plot generates a plot of digital readings vs. time in
seconds, like an oscilloscope. Graph generates a histogram, where the horizontal axis is the
reading and the vertical axis is the number of readings.

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6. MODBUS PROTOCOL IMPLEMENTATION
1. GENERAL
The Modbus capability conforms to the Modbus over Serial Line Specification & Implemen-
tation guide, V1.0. Both the Modbus RTU and Modbus ASCII protocols are implemented:
Modbus RTU
Baud Rate ........... .............................................. 300, 600, 1200, 2400, 4800, 600 or 1 200
Data Format ....... ........................ 1 start bit, 8 data bits, 1 parity bit, 1 stop bit (11 bits total)
Parity .................. ............................. None, Odd, Even (if None, then 2 Stop bits for 11 total)
Address .............. ............................................... 0 for broadcast, 1-247 for individual meters
Modbus ASCII
Baud Rate ........... .............................................. 300, 600, 1200, 2400, 4800, 600 or 1 200
Data Format ....... ...................... 1 Start bit, 7 Data bits, 1 Parity bit, 1 Stop bit (10 bits total)
Parity .................. ............................. None, Odd, Even (if None, then 2 Stop bits for 10 total)
Address .............. ............................................... 0 for broadcast, 1-247 for individual meters
2. FRAMING
Modbus RTU
Message frames are separated by a silent interval of at least 3.5 character times. If a silent
interval of more than 1.5 character times occurs between two characters of the message frame,
the message frame is considered incomplete and is discarded. Frame Check = 16 bit CRC of the
complete message excluding CRC characters.
Modbus ASCII
The message begins immediately following a colon (:) and ends just before a Carriage Return/
Line Feed (CRLF). All message characters are hexadecimal 0- , A-F (ASCII coded). The system
allowable time interval between characters may be set to 1, 3, 5 or 10 seconds. Frame Check =
1 byte (2 hexadecimal characters) LRC of the message excluding the initial colon (:) and trailing
LRC and CRLF characters.
3. ELECTRICAL INTERFACE
Four-wire (plus common) full-duplex or two-wire (plus common) half-duplex RS485 signal
levels are jumper selectable for digital panel meters, counters and timers. A polarization
resistor and termination resistor are also jumper selectable. In case of a long line (greater then
500 ft) to the first device, a termination resistor should be selected for the first device. In case
of a long line length (greater then 500 ft) between the first and last devices, a termination
resistor should be selected for the first and last devices. Never add termination resistors to
more than two devices on the same line. A two-wire, half-duplex RS485 signal level is jumper
selectable for transmitters.