Fuji Electric PXR3 Instruction Manual

Instruction Manual

MICRO CONTROLLER X COMMUNICATION FUNCTIONS (RS-485 MODBUS)

TYPE: PXR

INP-TN512642a-E

NOTICE

1. Exemption items from responsibility The contents of this document may be changed in the future without prior notice. We paid the utmost care for the accuracy of the contents. However, we are not liable for direct and

indirect damages resulting from incorrect descriptions, omission of information, and use of information in this document.

1. COMMUNICATION FUNCTIONS

1.1 General

2. SPECIFICATIONS

･･･････････････････････････････････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････････････････

2.1 Communication Specifications

3. CONNECTION

3.1 Terminal Allocation

3.2 Wiring

･･･････････････････････････････････････････････････････････････････････････････

･････････････････････････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････････････････････････

4. SETTING OF COMMUNICATION CONDITION

4.1 Set Items

4.2 Setting Operation Method

･･････････････････････････････････････････････････････････････････････････････････

･････････････････････････････････････････････････････････････････････

5. MODBUS COMMUNICATION PROTOCOL

5.1 General

5.2 Composition of Message

5.3 Response of Slave Station

5.4 Function Code

･･････････････････････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････････

･････････････････････････････････････････････････････････････････････････････

5.5 Calculation of Error Check Code (CRC-16)

5.6 Transmission Control Procedure

5.7 FIX Processing (Cautions at write-in of data)

6. DETAILS OF MESSAGE

6.1 Read-out of Bit Data ［Function code:01

･･･････････････････････････････････････････････････････････････

･････････････････････････････････････････････････････････････････

････････････････････････････････････････････････････

･･･････････････････････････････････････････････････････

･･････････････････････････････････････････････････････

･･･････････････････････････････････････････････････････････････

････････････････････････････････････････････････････

］

6.2 Read-out of Read-out Only Bit Data [Function code:02

････････････････････････････････････････････････････

6.3 Read-out of Word Data [Function code:03

]

6.4 Read-out of Read-out Only Word Data [Function code:04

･････････････････････････････････････････････････

6.5 Write-in of Bit Data (1 bit) [Function code:05

]

6.6 Write-in of Word Data (1 word) [Function code:06

6.7 Write-in of Continuous Word Data [Function code:10

7. ADDRESS MAP AND DATA FORMAT

7.1 Data Format

･･････････････････････････････････････････････････････････････････････････････

7.2 Address Map of Internal Calculation Value Data

7.3 Address Map of Engineering Unit Data

7.4 Additional Explanation of Address Map

･･････････････････････････････････････････････････････････

･･････････････････････････････････････････････････

･････････････････････････････････････････････････････････

････････････････････････････････････････････････････････

･････････････････････････････････････････････

]

･･････････････････････････････････････････

]

･･････････････････････････････････････････････

]

･･････････････････････････････････････････

]

8. SAMPLE PROGRAM

9. TROUBLESHOOTING

････････････････････････････････････････････････････････････････････････

－i－

1. COMMUNICATION FUNCTIONS

1.1 General

• PXR provides a communication function by RS-485 interface, by which it can transmit and receive data to and

from host computer, programmable controller, graphic display panel, etc.

• The communication system consists of master station and slave stations. Up to 31 slave stations (PXR) can

be connected per master station.

Note that, because the master station can communicate with only one slave station at a time, a party to

communicate with must be specified by the "Station No." set at each slave station.

• In order that the master station and slave station can communicate, the format of the transmit/receive data must

coincide. For the PXR, the format of the communication data is determined by the MODBUS protocol.

• Please use an RS-232C↔RS-485 converter in case of designating a personal computer or other devices which

have an RS-232C interface as a master station.

[RS-232C↔RS-485 converter] (recommended article)

Type: KS-485 (non-isolated type)/SYSTEM SACOM Corp. Type: SI-30A (isolated type)/SEKISUI ELECTRONICS Co., Ltd.

[Note] MODBUS

Programmable



controller

RS-485

is the registered trade mark of Gould Modicon.

Personal computer

RS-232C

RS-232C RS-485 converter

RS-485

－1－

2. SPECIFICATIONS

2.1 Communication Specifications

Item Specification Electrical specification Based on EIA RS-485 Transmission system 2-wire, semi-duplicate Synchronizing system Start-stop synchronous system Connection format 1 : N Number connectable units Up to 31 units Transmission distance 500m max. (total extension distance) Transmission speed 9600bps Data format

Transmission code HEX value (MODBUS RTU mode) Error detection CRC-16 Isolation Functional isolation between transmission circuit

Data length 8 bits Stop bit 1 bit Parity none, even, odd (selectable)

and others (withstand voltage : 500V AC)

－2－

3. CONNECTION

WARNING

For avoiding electric shock and malfunctions, do not turn on the power supply untill all wiring have been completed.

3.1 Terminal Allocation

Terminal number Signal name

7 + 8 -

－3－

3.2 Wiring

• Use twisted pair cables with shield.

Recommended cable: UL2464, UL2448, etc.

• The total extension length of the cable is up to 500 m. A master station and up to 31 units of the PXR can be

connected per line.

• Both ends of the cable should be terminate with terminating resistors 100Ω1/2W.

• The shield wire of the cable should be grounded at one place on the master station unit side.

• If the PXR is to be installed where the level of noise applied to the PXR may exceed 1000 V, it is

recommended to install a noise filter in the master station side as below.

Recommended noise filter: ZRAC2203-11/TDK

Master station

（

PC, etc.

）

RS-232C⇔RS-485

Master station side

Noise filter PXR

Transmission

cable

Slave station (PXR)

Twisted pair cable with shield

−

Terminating resistor 100Ω（1/2W）

RS-485 interface

RS-485 side of the RS-232C RS-485 converter

78＋

−

Slave station (PXR)

78＋

−

Slave station (PXR)

78＋

−

Terminating resistor 100Ω（1/2W）

－4－

In order that the master station and instrument (PXR) can correctly communicate, following settings are required.

SETTING OF COMMUNICATION CONDITION

• All communication condition settings of the master station are the same as those of instruments (PXR).

• All instruments (PXR) connected on a line are set to "Station Nos. (STno)" which are different from each other.

(Any "Station No." is not shared by more than one instrument.)

4.1 Set Items

The parameters to be set are shown in the following table. Set them by operating the front panel keys.

Parameter

symbol

――― ――― ―――

CoM Parity setting 0

STno Station No. 1

Transmission speed 9600bps Fixed (can not be changed) Data length 8 bits Fixed (can not be changed) Stop bit 1 bit Fixed (can not be changed)

Item

Value at delivery

Setting range Remarks

0: odd parity 1: even parity 2: none parity

0 to 255

(0:communication function stop)

Set the same communication condition to the master station and all slave stations.

Set a different value to each station.

－5－

4.2 Setting Operation Method

The following example shows how to set the communication conditions.

Example: Selecting an even parity and “STno=18” on a station.

Key

operation

SEL (6 seconds)

∨

SEL

∧∨

SEL

∨

SEL

∧∨

SEL

SEL (3 seconds)

Indication Description

200 200

P-n1

STno

CoM

200 200

Running state (PV/SV indication)

Press the SEL key for approximately 6 seconds. P-n1 appears and No. 3 block parameter is selected.

Operate the ∨ key repeatedly until STno parameter appears. (If past over, operate the ∧ key to return.)

Press the SEL key. The numeric value on the lower indicator blinks and the setting mode is selected.

Operate the ∧ or ∨ key to change the numeric value to 18.

Press the SEL key again. The numeric value stops blinking and the setting is registered.

Press the ∨ key to display the CoM parameter.

Press the SEL key. The numeric value on the lower indicator blinks and the setting mode is selected.

Operate the ∧ or ∨ key until the numeric value changes to 1 (even parity).

Press the SEL key again. The numeric value stops blinking and the setting is registered.

Press the SEL key for 3 seconds to resume the running indication (PV/SV indication).

－6－

5. MODBUS COMMUNICATION PROTOCOL

5.1 General

The communication system by the MODBUS protocol is that the communication is always started from the master

station and a slave station responds to the received message.

Transmission procedures is as shown below.

1） The master station sends a command message to a slave station. 2） The slave station checks that the station No. in the received message matches with the own station No. or

not.

3） If matched, the slave station executes the command and sends back the response message.

4) If mismatched, the slave station leaves the command message and wait for the next command message.

a) In case when the station No. in the received command message matches with the own slave station No.

Master to slave

Slave to master

b) In case when the station No. in the received command message mismatches with the own slave station

No.

Master to slave

Slave to master

The master station can individually communicate with any one of slave stations connected on the same line upon

setting the station No. in the command message.

Command message

Response message

(Not respond)

Data on

the line

Data on

the line

－7－

5.2 Composition of Message

Command message and response message consist of 4 fields ; Station No., Function code, Data and Error check

code. And these are send in this order.

Station No. (1 byte)

Function code (1 byte)

Data (2 to 125 bytes)

Error check code (CRC-16) (2 bytes)

Fig. 5-1 Composition of message

In the following, each field is explained.

(1) Station No.

Station No. is the number specifiing a slave station. The command message is received and operated only by

the slave station whose station No. matches with the No. set in the parameter "STno".

For details of setting the parameter "STno", refer to chapter 4.

(2) Function code

This is a code to designate the function executed at a slave station.

For details, refer to section 5.4.

(3) Data

Data are the data required for executing function codes. The composition of data varies with function codes.

For details, refer to chapter 6.

A coil number or a register number is assigned to each data in the temperature controller. For reading/writing

the data by communication, designate the coil number or register number.

Note that the coil number or register number transmitted on message is expressed as its relative address.

The relative address is calculated by the following expression.



The lower 4 digits of the

Relative address

For example, when the resister number designated by a function code is 40003, Relative address = (lower 4 digits of 40003) – 1

= 0002

is used on the message.

＝

 

Coil number or register number



– 1

 

－8－

(4) Error check code

This is the code to detect message errors (change in bit) in the signal transmission.

On the MODUBUS protocol (RTU mode), CRC-16 (Cycric Redundancy Check) is applied.

For CRC calculation method, refer to section 5.5.

－9－

5.3 Response of Slave Station

(1) Response for normal command

To a relevant message, the slave station creates and sends back a response message which corresponds to the

command message. The composition of message in this case is the same as in section 5.2.

Contents of the data field depend on the function code. For details, refer to Chapter 6.

(2) Response for abnormal command

If contents of a command message have an abnormality (for example, non-actual function code is designated)

other than transmission error, the slave station does not execute that command but creates and sends back a

response message at error detection.

The composition of response message at error detection is as shown in Fig. 5-2 The value used for function

code field is function code of command message plus 80

Table 5-1 gives error codes.

Station No.

Function code + 80H

Error code

Error check（CRC-16）

Fig. 5-2 Response message at error detection

Table 5-1 Error code

Error code Contents Description

01H Illegal function Non-actual function code is designated.

Check for the function code.

02H Illegal data address A relative address of a coil number or resister

number to which the designated function code can not be used.

03H Illegal data value Because the designation of number is too much,

the area where coil numbers or resister numbers do not exist is designated.

(3) No response

Under any of the following items, the slave station takes no action of the command message and sends back no

response.

・A station number transmitted in the command message differs from the station number specified to the

slave station.

・ A error check code is not matched, or a transmission error (parity error, etc.) is detected. ・ The time interval between the composition data of the message becomes longer than the time

corresponding to 24 bits. (Refer to section 5.6 Transmission Control Procedure)

・While the data is being written in non-volatile memory after write via communication, the next write is

attempted.

－10－

5.4 Function Code

According to MODBUS protocol, coil numbers and register numbers are assigned by function codes.

Each function code acts on specific coil number and register number.

This correspondence is shown in Table 5-2, and the message length by function is shown in Table 5-3.

Table 5-2 Correspondence between function codes and objective address

Function code

No. Function Object 01H Read-out

Coil

0xxxx Read-out/write-in bit data

Coil No. and resister No.

No. Contents

(continuously)

02H Read-out

Input relay

1xxxx Read-out bit data

(continuously)

03H Read-out

Holding register

4xxxx Read-out/write-in word data

(continuously)

04H Read-out

Input register

3xxxx Read-out word data

(continuously) 05H Write-in Coil 06H Write-in Holding register 10H Write-in

Holding register

0xxxx Read-out/write-in bit data 4xxxx Read-out/write-in word data 4xxxx Read-out/write-in word data

(continuously)

Table 5-3 Function code and message length

[Unit:byte]

Function

code

Contents Number of

designatable

Command message Response message

Minimum Maximum Minimum Maximum

data

01H Read-out of bit data 1bit 02H Read-out of bit data (read-out only) 8 bits 03H Read-out of word data 60 words 04H Read-out of word data

15 words

8 8 6 6 8 8 6 6 8 8 7 125 8 8 7 35

(read-out only) 05H Write-in of bit data 1 bit 8 8 8 8 06H Write-in of word data 1 word 8 8 8 8 10H Write-in of continuous word data 60 words

11 129 8 8

*1) The "Number of designatable data" given above is the limit due to the number of data which the instrument

assigns to coil number and register number (except function codes 05

, 06H).

－11－

5.5 Calculation of Error Check Code (CRC-16)

CRC-16 is the 2-byte (16-bits) error check code. From the top of the message (station No.) to the end of the

data field are calculated.

The slave station calculates the CRC of the received message, and does not respond if the calculated CRC is

different from the contents of the received CRC code.

Fig. 5-3 shows the flow of the CRC-16 calculation system.

Start

Set FFFFH (hexadecimal number) in CR.

Set 1 in J.

Exclusive logical sum (XOR) is executed with CR and one character (1 byte) of the I characters, and its results is set in CR.

Set 1 in J.

Bit at right end

of CR is 1?

YES

Shift CR to right by 1 bit, and A001H and exclusive logical sum (XOR) are executed and its result is set in CR.

Explanation of variables

CR:CRC error check data (2 bytes)

I:Digits of calculation characters

in command message

J:Check on the number of times

of CR calculation

Shift CR to righ by 1 bit.

Add 1 to J.

Calculation (8 times) is finished?

J>8

YES

Add 1 to J.

Calculation of all characters is

completed?

I>All characters

YES

End

Fig. 5-3 Flow of CRC-16 calculation

(Calculation is executed in the order of command message station No., function code and data.)

CR calculation result shall be added to the last command message in the order of LOW byte and HIGH byte.

－12－

5.6 Transmission Control Procedure

(1) Transmission procedure of master station

The master station must proceed to a communication upon conforming to the following items.

(1-1) Before sending a command message, provide 48 bits time or more vacant status.

(1-2) For sending, the interval between bytes of a command message is below 24 bits time.

(1-3) Within 24 bits time after sending a command message, the receiving status is posted.

(1-4) Provide 48 bits time or more vacant status between the end of response message reception and

beginning of next command message sending [same as in (1-1)].

(1-5) For ensuring the safety, make a confirmation of the response message and make an arrangement so

as to provide 3 or more retries in case of no response, error occurrence, etc.

Note) The above definition is for most unfavorable value. For ensuring the safety, it’s recommended the

program of the master to work with safety factors of 2 to 3. Concretely, it is advised to arrange the

program for 9600 bps with 10 ms or more for vacant status (1-1), and within 1 ms for byte interval (1-2)

and changeover from sending to receiving (1-3).

(2) Description

1) Detection of the message frame

Since the communication system uses the 2-wire RS-485 interface, there may be 2 statuses on a line below.

(a) Vacant status (no data on line) (b) Communication status (data is existing)

Instruments connected on the line are initially at a receiving status and monitoring the line. When 24 bits

time or more vacant status has appeared on the line, the end of preceding frame is assumed and, within

following 24 bits time, a receiving status is posted. When data appears on the line, instruments receive it

while 24 bits time or more vacant status is detected again, and the end of that frame is assumed. I.e., data

which appeared on the line from the first 24 bits time or more vacant status to the next 24 bits time or more

vacant status is fetched as one frame.

Therefore, one frame (command message) must be sent upon confirming the following.

(1-1) 48 bits time or more vacant status precedes the command message sending.

(1-2) Interval between bytes of 1 command message is smaller than 24 bits time.

2) Response of this instrument (PXR)

After a frame detection (24 bits time or more vacant status), this instrument carries out processing with that

frame as a command message. If the command message is destined to the own station, a response

message is returned. Its processing time is 1 to 30 ms (depends on contents of command message).

After sending a command message, therefore, the master station must observe the following.

(1-3) Receiving status is posted within 24 bits time after sending a command message.

－13－

+ 36 hidden pages

Fuji Electric PXR3 Instruction Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

CONTENTS

2.1 Communication Specifications

SETTING OF COMMUNICATION CONDITION

4.2 Setting Operation Method

5. MODBUS COMMUNICATION PROTOCOL

5.2 Composition of Message

5.3 Response of Slave Station

Function code

5.5 Calculation of Error Check Code (CRC-16)

5.6 Transmission Control Procedure