Hitachi Sj7002 Owners Manual

							Communications Reference Information
Appendix B
B–18
Communications Reference Information
Inverter
Affirmative ReplyThe standard affirmative reply from the inverter 
uses the ACK character (acknowledge) in the data 
field. The frame format of this reply follows the 
diagram and specification table.
Inverter
Negative ReplyThe standard negative reply from the inverter 
uses the NAK character (negative acknowl-
edge) in the data field. The frame format of 
this reply follows the diagram and specifica-
tion table.
The error codes for a NAK (negative acknowledge) are:
If a host computer broadcasts a command to all inve rter stations, no response will be returned 
to the host.
ElementDescriptionSizeVa l u e
STX Control code (STart of TeXt) 1 byte STX (0x02)
Node Node (station) address  of inverter 2 bytes 01 to 32
ACK Control code (ACKnowledge) 1 byte ACK (0x06)
BCC Block check sum code 2 bytes Exclusive OR of Node and ACK
[CR] Control code (carriage return) 1 byte [CR] (0x0D)
STXNode ACK BCC [CR]
Frame format
ElementDescriptionSizeVa l u e
STX Control code (STart of TeXt) 1 byte STX (0x02)
Node Node (station) address  of inverter 2 bytes 01 to 32
NAK Control code (Negative ACKnowledge) 1 byte NAK (0x15)
Error code Code representing error  type 2 bytes (See next table below)
BCC Block check sum code 2 bytes Exclusive OR of Node, Data,   and NAK
[CR] Control code (carriage return) 1 byte [CR] (0x0D)
Error  CodeError DescriptionError  CodeError Description
01H Parity error 07H Receive buffer overrun error
02H Check sum error 08H Receive time-out error
03H Framing error 11H Abnormal command code error
04H Overrun error 13H Execution disabled
05H Protocol error 16H Abnorm al parameter code/value 
error
06H ASCII code error — —
Node BCC [CR]
Frame formatSTXNAK
Error
code

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							SJ7002 Inverter
Appendix B
B–19
Block Check 
Code (BCC)This section shows how the inverter protocol computes defines a BCC—block check code. The 
BCC is calculated for each frame transmitted and  can be used to verify the integrity of data 
transmission. The example below shows command  01 setting the inverter frequency to 5Hz.
The block check code is computed by using  the ASCII codes (shown above) and applying 
eXclusive OR (XOR) operations. Beginning with the  first pair of bytes, the result of their XOR 
result is then used in an XOR operation with th e third byte, and so on. For this example, the 
BCC calculation is shown below.
ASCII Code TableThe table below shows only the ASCII codes us ed for function codes and parameter data.
STXNode Command Data BCC [CR]
Frame format
ASCII Code
(0x 02)
(0x 30 31)
(0x 30 31)
(0x 30 30 30 35 30 30)
(0x 30 35)
(0x 0D)
0 1
0 1
0 0 0 5 0 0
0
Data bytes:
3 03 0
3 53 03 0
3 03 1
3 03 1
0 1 3 0
3 1
0 0
3 0
0 0
3 0
0 5
3 5
0 5BCCXOR
intermediate results
CharacterASCII CodeCharacterASCII CodeCharacterASCII Code
STX 0 2 43 4 C4 3
ACK 0 6 53 5 D4 4
CR 0 D 63 6 E4 5
NAK 1 5 73 7 F4 6
0 3 0 838 H4 8
1 3 1 939 P5 0
23  2A4  1b6 2
33  3B4  2
——

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							Communications Reference Information
Appendix B
B–20
Communication 
Test ModeThe communication test mode verifies that the inverter can properly send and receive data via 
the RS485 serial port. Follow the steps  below to perform the communication test.
1. Remove the serial cable (if pr esent) connected to the TM2 co nnector block of the control 
terminals, as shown below.
NOTE:  It is not necessary to connect a loopback ju mper. The RS485 port uses a transceiver for 
communications, which already allows simultaneous transmitting and receiving.
2. Use the front panel keypad to navigate to parameter C071,  Communication Speed
Selection. Change parameter  C071=02 and press Store. Value 02 is the Loopback Test 
option. Now the inverter is ready to conduct the loopback test.
3. Turn the inverter power OFF and then ON again  to initiate the communication test. Observe 
the keypad display and compar e to the results shown below.
4. Press the Stop/Rest button on the keypad to retu rn the inverter keypad/ display to normal 
operation.
5. Change C071 to its original setting (default is C071=04). Otherwise, while C071=02, the 
inverter will perform the communicati ons loopback test at each powerup.
SPSNRPSN
Serial
communications
TM2
PASS FAIL

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							SJ7002 Inverter
Appendix B
B–21
ModBus Mode Communications
Transmission 
ProcedureThe network master sends a frame to initiate communications with a slave, as shown in the 
figure below.
 Query - A frame sent from the external control equipment to the inverter
 Response - A frame returned from the inve rter to the external control equipment
 Wait time (C077) - If the inverter cannot complete the reception of a query from the host  (master)within the communicatio n timeout period, the inverter responds to the query and 
waits to receive the query from the beginning. Su bsequently, the inverter returns no response 
to the master system.
After reception timeout occurs, the inverter  operates according to function C076, Action 
upon communication error select ion (see table below). Monitoring of reception timeout 
begins when the first communication is pe rformed upon inverter powerup or a reset. 
Reception timeout is monitored only when  the inverter communicates with the master 
system.
The inverter always sends a response frame afte r receiving a query frame. The inverter does not 
initiate any communication with the host (master).
Function  CodeName/DescriptionOPERange and Settings
C076 Action upon communi-
cation error selection 00 Trip (E41)
01 Trip (E41) after 
deceleration and stop
02 No action (ignore errors)
03 Free-run stop
04 Decelerate and stop
C077 Communication timeout before trip 0.00 to 99.99 (seconds)
Limit timer for reception timeout
C078 Communication wait time 0.0 to 1000 (milliseconds)
Time to wait until the inverter starts 
sending a response after reception 
of a query (excluding the silent 
interval)
Host
(master)
Latency time (silent interval plus C078 setting)
Query
Inverter (slave) Response
Transmitting device:

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							ModBus Mode Communications
Appendix B
B–22
Message Config-
uration: QueryEach frame is formatted as follows:
Slave address:
 This is a numer from 1 to 32 assigned to each inverter (slave). (Only the inverter having the address given as a slave address in the query can receive the query.)
 When slave address “0” is specified, the query  can be addressed to all inverter simultane-
ously (broadcasting).
 In broadcasting, the host (master) cannot read  inverter data nor perform a loopback test.
Data:
 The data contains a function command.
 The data format used in the SJ700
2 corresponds to the ModBus data format below.
Function Code:
Specify a function you want to make the inverter execute. Function codes available to the 
SJ700
2 are listed below.
Error check:
Modbus-RTU uses CRC (Cyclic Redund ancy Check) for error checking.
 The CRC code is 16-bit data that is gene rated for 8-bit blocks of arbitrary length.
 The CRC code is generated by  a generator polynomial CRC-16 (X
16+ X15+ X2+ 1).
Frame Format
Header (silent interval)
Slave address
Function code
Data
Error check code
Trailer (silent interval)
Name of DataDescription
Coil Binary data that can be referenced and changed (1 bit long)
Holding Register 16-bit data that  can be referenced and changed
Function 
CodeFunction
Maximum data size (bytes available per  message)Maximum number of data elements per  message
01h Read Coil Status 4 32 coils (in bits)
03h Read Holding Register 8 4 registers (in bytes)
05h Write in Coil 2 1 coil (in bits)
06h Write in Holding Regist er 2 1 register (in bytes)
08h Loopback Test — —
0Fh Write in Coils 4 32 coils (in bits)
10h Write in Registers 4 4 registers (in bytes)

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							SJ7002 Inverter
Appendix B
B–23
Header and trailer (silent interval):
Latency is the time between the reception of a query from the master and transmission of a 
response from the inverter.
 The header and trailer set the total time the  inverter should wait before sending a response 
after having received a query from the master system.
 Be sure to specify the time corresponding to the transmission of 3.5 characters (24 bits) as  the waiting time. If a shorter waiting time (co rresponding to the transmission of fewer than 
3.5 characters) is specified, the inverter will not respond.
 The actual waiting time is the sum of the sile nt interval (corresponding to the transmission of 
3.5 characters) and the communication wait time (C078).
Message 
Configuration: 
ResponseTime required for communication:
 After the inverter receives a query, the inverter  waits for the sum of the silent interval (corre-
sponding to the transmission of 3.5 characters) and the communicat ion wait time (C078) 
before sending a response.
 After receiving a response from the inverter,  the master system must wait for the silent 
interval (corresponding to the transmission  of 3.5 characters) or longer before sending the 
next query to the inverter.
Normal response:
 If the query specifies the function code (08h) for the loopback test, the inverter returns a  response that has the same contents as the query.
 If the query specifies a function  code (05h, 06h, 0Fh, or 10h) for writing data to registers or 
coils, the inverter returns the query  without a change as a response.
 If the query specifies a function  code (01h or 03h) for reading a register or coil, the inverter 
returns a response that contains the slave address and function code specified in the query 
and the data read from the register or coil.
Response when an error occurs:
 When finding any error in a query (except for a  transmission error), the inverter returns an 
exception response without executing anything,
 You can check the error by the function code  in the response. The function code of the 
exception response is the sum of the  function code of the query and 80h.
 The content of the error is  known from the exception code.
   
Field Configuration
Slave address
Function code
Exception code
CRC–16
Exception CodeDescription
0 1 h The specified function is not supported.
0 2 h The specified address is not found.
0 3 h The format of the specified data is not acceptable.
2 1 h The data to be written in a holding register is outside the inverter.

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							ModBus Mode Communications
Appendix B
B–24
No response occurs:
In the cases below, the inverter ignores a query and returns no response.
 When receiving a broadcasting query
 When detecting a transmission  error in reception of a query
 When the slave address set in the query is not equal to the slave address of the inverter
 When a time interval between data elements constituting a message is shorter than  3.5 characters
 When the data length of the query is invalid
NOTE: Provide a timer in the master and make the  master retransmit the same query when no 
response is made within a preset time period after the preceding query was sent.
2 2 h The specified functions are not available to the inverter.
•Function to change the content of  a register that cannot be changed 
while the inverter is in service
•
Function to submit an ENTER command during running (UV)
•Function to write in a re gister during tripping (UV)
•Function to write in a read-only register (or coil)
Exception CodeDescription

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							SJ7002 Inverter
Appendix B
B–25
Explanation of 
Function CodesRead Coil Status [01h]:
This function reads the status (ON/OFF) of selected coils. An example follows below.
 Read intelligent input terminals [1] to [6]  of an inverter having a slave address “8.”
 This example assumes the intelligent input terminals have terminal states listed below  (coils 13 and 14 are OFF).
 The data set in the response shows  terminal states of coils 7 to 14.
 Data “17h = 00010111b” indicates the fo llowing assuming coil 7 is the LSB.
 When a read coil is outside the defined coils,  the final coil data to be transmitted contains 
“0“as the status of the coil outside the range.
 When the Read Coil Status command cannot  be executed normally, see the exception 
response.
ItemData
Intelligent input terminal [1] [2] [3] [4] [5] [6]
Coil number 7 8 9 10 11 12
Terminal status ON ON ON OFF ON OFF
ItemData
Coil number 14 13 12 11 10 9 8 7
Coil status OFF OFF OFF ON OFF ON ON ON
Query:
Note 1: Broadcasting is disabled.
Note 2: The starting coil number is one 
less than the number of the coil to 
be read first.
Note 3: When 0 or more than 32 is 
specified as a number of coils, 
error code “03h” is returned. Response:
Note 4:
Data is transferred by the specified 
number of data bytes (data size).
No.Field NameExample 
(hex)
1 Slave address *1 08
2 Function code 01
3 Coil start number  (high order) 00
4 Coil start number (low  order) 06
5 Number of coils (high  order) *2 00
6 Number of coils (low  order) *2 06
7 CRC-16 (high order) 5C
8 CRC-16 (low order) 90No.Field NameExample  (hex)
1 Slave address 08
2 Function code 01
3 Data size (in bytes) 01
4 Coil data *4 17
5 CRC-16 (high order) 12
6 CRC-16 (low order) 1A

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							ModBus Mode Communications
Appendix B
B–26
Read Holding Register [03h]:
This function reads the contents of the specified number of consecutive holding registers (of 
specified register addresses) . An example follows below.
 Reading previous three trip factors from  an inverter having a slave address “5”
 This example assumes the previous  three trip factors are as follows:
The data set in the response is as follows:
When the Read Holding Register command cannot be executed normally, refer to the exception 
response.
SJ7002 CommandD081 (N)D082 (N-1
Register number 0012h0013h
Trib factor (upper digit) Over -voltage (E07)Decelerating (02)
Response Buffer4567
Starting register 
number +0 (high order) +0 (low order) +1 (high order) +1 (low order)
Register status 00h 07h 00h 02h
Trip data Over-voltage trip Decelerating
Query:
Note 1: Broadcasting is disabled.
Note 2: The starting coil number is one 
less than the number of the coil to 
be read first. Response:
Note 3:
Data is transferred by the specified 
number of data bytes (data size). In 
this case, 4 bytes are used to return 
the content of two holding 
registers.
No.Field NameExample 
(hex)
1 Slave address *1 05
2 Function code 03
3 Register start number  (high order) 00
4 Register start number  (low order) 11
5 Number of registers  (high order) *2 00
6 Number of registers  (low order) *2 02
7 CRC-16 (high order) 95
8 CRC-16 (low order) 8ANo.Field NameExample  (hex)
1Slave address 05
2 Function code 03
3 Data size (in bytes) *3 04
4 Register start number  (high order) 00
5 Register start number  (low order) 07
6 Register start number +1  (high order) 00
7 Register start number +1  (low order) 02
8 CRC-16 (high order) 36
9 CRC-16 (low order) 37

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							SJ7002 Inverter
Appendix B
B–27
Write in Coil [05h]:
This function writes data in a single coil. Coil status changes are as follows:
An example follows (note that to command the inverter, set A002=03):
 Sending a RUN command to an inverter having slave address “10”
 This example writes in coil number “1.”
When the Write in Coil command cannot be execut ed normally, refer to the exception response.
Write in Holding Register [06h]:
This function writes data in a specifie d holding register. An example follows below.
 Write “50Hz” as the first Mu lti-speed 0 (A020) in an inverter having slave address “5.”
 This example uses change data “50 (0032h)” to  set “50Hz” as the data resolution of the 
register “1203h” holding the base  frequency setting (A003) is 1 Hz. 
Data
Coil Status
OFF to ONON to OFF
Change data (high order) FFh 00h
Change date (low order) 00h 00h
SJ7002 CommandD081 (N)D082 (N-1
Register number 0012h0013h
Trib factor (upper digit) Over-v oltage (E07)Decelerating (02)
Query:
Note 1:Broadcasting is disabled.
Note 2: The starting coil number is one 
less than the number of the coil to 
be read first. Response:
No.Field NameExample 
(hex)
1 Slave address *1 0A
2 Function code 05
3 Coil start number (high  order) 00
4 Coil start number (low  order) *2 00
5 Change data (high  order) FF
6 Change data (low order) 00
7 CRC-16 (high order) 8D
8 CRC-16 (low order) 41No.Field NameExample  (hex)
1Slave address 0A
2 Function code 05
4 Coil start number (high  order) 00
5 Coil start number (low  order) 00
6 Change data (high  order) FF
7 Change data (low order) 00
8 CRC-16 (high order) 8D
9 CRC-16 (low order) 41

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