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ROOTECH ACCURA 7500 User Manual

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ACCURA 7500
Integrated Digital Protection Relay
+ High Accuracy Power Meter
Communication User's Manual[English]
Rev 1.0

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  • Page 1 ACCURA 7500 Integrated Digital Protection Relay + High Accuracy Power Meter Communication User’s Manual[English] Rev 1.0...
  • Page 2 Indicates alternative voltage or current. Indicates direct voltage or current. Installation Considerations The installation and operation of Accura 7500 should be performed only by qualified, competent personnel that have received appropriate training and experience with high voltage and current devices.
  • Page 3 - Barrier-type digital inputs/digital output terminal: 0.90Nm (9 kgf∙cm = 0.66 lbf∙ft) max. About the Manual Rootech Inc. reserves the right to make changes in the device specifications shown in this User Guide without notice. Therefore, we recommend that customers should obtain the latest information on specifications of the device before making orders.
  • Page 4 Rootech will decide at its discretion whether to repair or replace it or give a refund for the product for when the warranty period for the product expired or issues related to the product are not applicable for warranty terms and conditions.
  • Page 5 Rootech shall not be liable for any other claims except the claims made by customers, including the original purchaser, his employees, agents, or contractors for any loss, damage, or expense incurred related to the purchased product when the above warranty terms and conditions are not fulfilled.
  • Page 6 Standard Compliance Process Control Equipment E324900 Page 6...
  • Page 7 Revision History The following versions of the Accura 7500 Communication User Guide has been released. Revision Date Description Revision 1.0 November 11, 2020 First issue Page 7...

  • Page 8: Table Of Contents

    Contents Chapter 1 Serial Communication ........................11 Serial Communication ..........................11 Accura 7500 Communication ........................ 12 Chapter 2 Communication Wiring/Setup ....................14 Communication Wiring .......................... 14 Communication Setup ..........................15 Setup Mode ..................................16 Chapter 3 Modbus RTU Protocol ........................18 Packet Field of Modbus RTU ............................
  • Page 9 Protection Part ............................36 DIO Status and Control section ..........................36 Measurement section † ..............................38 Reset section ..................................39 Maintenance section ............................... 39 Event Record section ..............................40 † Captured (Event) Waveform section ........................41 Auxiliary Function 1 Setup section .......................... 42 Auxiliary Function 2 Setup section ..........................
  • Page 10 Measurement Value Calculation ......................68 Fixed Scale ................................... 68 Variable Scale ..................................68 APPENDIX A CRC-16 Calculation ........................70 CRC-16 Generation ..........................70 CRC Generation procedure............................70 APPENDIX B Modbus RTU C Code Example ....................72 Data Reception and CRC Generation & Checking ................72 Request Packet Generation ............................

  • Page 11: Chapter 1 Serial Communication

    Serial Communication Accura 7500 has a RS-485 port supporting multi-drop operations for communication between Master and Slave devices. In order to communication with host system, Accura 7500 supports Modbus RTU protocol for general users. Modbus RTU protocol is used for connection with automation equipment such as PC and PLC, and as an industrial standard, it allows users to efficiently transfer measurement and setup data between master[PC, PLC, or etc.] and slave[Accura 7500] devices.

  • Page 12: Accura 7500 Communication

    232 converter[RTS/CTS automatic control required] should be used. For communication between a PC and Accura 7500, the RS-485 Data+(TRX) and Data-(TRX) lines of the converter should be connected to the Ta and Tb ports on Accura 7500, respectively. The RS-232 port of the converter is connected to the user PC.
  • Page 13 5ms. At least 10ms is required for packet recognition. . Holding Time before Transmitting Request Packet After receiving data from Accura 7500, the PC[Master] should send a next request packet in at least 10msec[17 msec at 38400bps]. Caution should be taken when Accura 7500 sends the request packet right after receiving data in case of making a request for high-speed data transfer.

  • Page 14: Chapter 2 Communication Wiring/Setup

    Maximum number of connected devices per bus Note It is recommended to use a cable that complies with the UL2919 standard. Communication LED Indicator The Comm LED on the front of Accura 7500 blinks yellow when it transmits data. Page 14...

  • Page 15: Communication Setup

    Communication Setup As shown below, Accura 7500 features the meter and protection relay sections located on the left and right side from the center line. Fig 2.1 Screen Composition on the Front Protection relay Meter The control method and screen composition of the meter part is same to those of Accura 3300 and 3500.

  • Page 16: Setup Mode

    Setup Mode After installing Accura 7500, set the PT/CT ratio, wiring methods, and communication modes that fit the operational environment of the device . Button functions in the setup mode Button Function Moves to the setup mode display Moves to the previous menu.
  • Page 17 Connection method 3-Phase 3-Wire 2PT(Open Delta) 3-Phase 3-Wire 3PT(Wye) 3-Phase 4-Wire √ Communication 1 ~ 247 address Protocol Modbus RTU √ Rootech Baud rate [bps] 1200bps 2400bps 4800bps 9600bps √ 19200bps 38400bps Parity bit Even parity √ Odd parity None parity 1 ~ 2 Used for manufacturers only.

  • Page 18: Chapter 3 Modbus Rtu Protocol

    The slave address field of a Modbus RTU packet is one byte in length. It is used as an ID to specify the slave device[Accura 7500] during communication. A valid address ID for the relay ranges from 1 to 247. You should specify a slave address[the relay’s ID] from which you want to receive data and make a request for the address.

  • Page 19: Error Check Field

    2 bytes Exception Responses If a master device sends an invalid command to the slave[Accura 7500] or attempts to read an invalid holding register, an exception response will be generated from Accura 7500. To indicate an error in the exception response, the high order bit of the function code is set to 1.

  • Page 20: Broadcast Packets

    Broadcast Packets A broadcast request packet allows the master device to send the same commands to multiple slave devices simultaneously. A broadcast request packet is the same as a normal request packet, except the slave address field is set to zero. All Slave devices receive and perform broadcast request commands.

  • Page 21: Packet Communication

    Packet Communication Accura 7500 has the following Modbus functions. Function 03: Read Holding Registers To read the relay’s parameter values, the master sends the slave device a Read Holding Registers request packet. The Read Holding Registers request packet specifies the starting address of the Holding Register and the word count of the registers to read.

  • Page 22: Function 06: Write A Single Register To Meter

    Function 06: Write a Single Register to Meter To write data to a single register, a Master should send the slave device a Write Single Register to Meter request packet via Function 06 code. Request Slave Function Starting Address Data Word Error Check 1 byte 1 byte...

  • Page 23: Reserved Registers

    Starting Address indicates the Starting Address for the data to be set. Word Count indicates the number of data to be set, and Byte Count is twice the Word Count. Example] Writes data1[78hex] and data2[0xA] to the PT ratio [address 40053] and CT ratio [address 40054] of the relay 1.

  • Page 24: Chapter 4 Modbus Rtu Map

    Chapter 4 Modbus RTU Map Address Map Sections Overview Address Section Descriptions 40001 - 40015 System Information Product model, version, calibration 40016 - 40050 Invalid Meter Part 40051 - 40066 Configuration Communication id, PT/CT ratio, protocol, baud rate, parity bit, stop bit, demand time 40067 - 40100 Invalid...
  • Page 25 43011 - 43030 Invalid 43031 - 43049 Auxiliary-function 2 PT Failure Detection, CB Failure Detection, Protection Block 43050 Invalid 43051 - 43063 Digital Input Setup Digital Input Setup 43064 - 43070 Invalid 43071 - 43095 Digital Output Setup CB, Alarm, DO1-DO10 43096 - 43100 Invalid 43101 - 43156...

  • Page 26: System Information Section

    UINT16 2500 = Accura 2500 3300 = Accura 3300 3500 = Accura 3500 3550 = Accura 3550 7500 = Accura 7500 7800 = Accura 7800 1010 = RTM 010 1050 = RTM 050 1100 = RTM 100 1200 = RTM 200...

  • Page 27: Meter Part

    0 = 60Hz 1 = 50Hz 40066 Reserved UINT16 Invalid UINT16 ••• ••• 40100 Invalid UINT16 Refer to “Accura 7500 User Manual” for detailed information on the method. † Measurement section † Address Attribute Measurement Format Scale Descriptions 40101 Voltage a...
  • Page 28 40104 Voltage average UINT16 VSA[40109] 40105 Line Voltage ab UINT16 VSA[40109] 40106 Line Voltage bc UINT16 VSA[40109] 40107 Line Voltage ca UINT16 VSA[40109] 40108 Line Voltage average UINT16 VSA[40109] 40109 Voltage scale UINT16 40110 Current a UINT16 VSB[40118] 40111 Current b UINT16 VSB[40118] 40112...

  • Page 29: Thd, K Factor

    THD, K Factor Address Attribute Measurement Format Scale † Descriptions 40148 THD of Voltage a UINT16 x0.1 40149 THD of Voltage b UINT16 x0.1 40150 THD of Voltage c UINT16 x0.1 40151 THD of Current a UINT16 x0.1 40152 THD of Current b UINT16 x0.1 40153...

  • Page 30: Demand, Maximum, And Minimum Section

    Demand, Maximum, and Minimum section Address Attribute Measurement Format Scale † Descriptions 40301 Total kW demand INT16 VSB[40302] 40302 Total kW demand Scale UINT16 40303 Total kVAR demand INT16 VSB[40304] 40304 Total kVAR demand Scale UINT16 40305 Total kVA demand INT16 VSB[40306] 40306...

  • Page 31: Extra Predicted Demand Section

    40343 kW c maximum INT16 VSB[40344] 40344 kW maximum Scale UINT16 40345 Total kW maximum INT16 VSB[40346] 40346 Total kW maximum Scale UINT16 40347 kVAR a maximum INT16 VSB[40350] 40348 kVAR b maximum INT16 VSB[40350] 40349 kVAR c maximum INT16 VSB[40350] 40350 kVAR maximum Scale...

  • Page 32: Harmonic Section

    Harmonic section Address Attribute Measurement Format Scale † Descriptions 40401 DC voltage a[%] UINT16 x0.1 40402 harmonic of Voltage a [%] UINT16 x0.1 40403 harmonic of Voltage a [%] UINT16 x0.1 UINT16 x0.1 ••• ••• ••• 40432 harmonic of Voltage a [%] UINT16 x0.1 40433...

  • Page 33: Vector Diagram Section

    Vector diagram section † Address Attribute Measurement Format Scale ‡ Descriptions 40593 Voltage a x INT16 40594 Voltage a y INT16 40595 Voltage b x INT16 40596 Voltage b y INT16 40597 Voltage c x INT16 40598 Voltage c y INT16 40599 Reserved...

  • Page 34: Waveform Section

    Waveform section Address Attribute Measurement Format Scale † Descriptions 40607 Waveform Update Flag[IrDA port] UINT16 Write[0xFF] = Update Request Read[0x00]= Update Done 40608 Waveform Update Flag[RS485 port] UINT16 Write[0xFF] = Update Request Read[0x00]= Update Done 40609 Waveform data of Voltage a INT16 40610 Waveform data of Voltage a...

  • Page 35: Demand Trend Section

    Demand trend section Attribute Measurement Format Scale † Descriptions Address Total kW demand trend value1 INT16 VSB[41097] 41001 Total kW demand trend value2 INT16 VSB[41097] 41002 ••• ••• INT16 VSB[41097] ••• Total kW demand trend value96 INT16 VSB[41097] 41096 Total kW demand trend value Scale UINT16 41097 Invalid...

  • Page 36: Protection Part

    Protection Part DIO Status and Control section Address Attribute Measurement Format Descriptions Digital Input / Output Status and On/Off Control 41201 Digital Input channel 1 UINT16 0x00FF = On 0x0000 = Off 41202 Digital Input channel 2 UINT16 0x00FF = On 0x0000 = Off 41203 Digital Input channel 3...
  • Page 37 0x0000 = None 41224 Alarm Output channel UINT16 0x00FF = On 0x0000 = Off Fault Status 1 (Relay Operated) 41225 Phase A Fault UINT16 Refer to “Value Table T14” 41226 Phase B Fault UINT16 Refer to “Value Table T14” 41227 Phase C Fault UINT16 Refer to “Value Table T14”...

  • Page 38: Measurement Section

    Measurement section † Address Attribute Measurement Format Descriptions 41501 Fundamental voltage A S1 UINT16 41502 Fundamental voltage B S1 UINT16 41503 Fundamental voltage C S1 UINT16 41504 Fundamental voltage G S1 UINT16 Ground voltage (Vg) 41505 Positive sequence voltage (Va1) S1 UINT16 41506 Negative sequence voltage (Va2)

  • Page 39: Reset Section

    Reset section Address Attribute Measurement Format Descriptions 41601 Maximum fundamental value Reset UINT16 0x00FF = Reset Request 0x0000 = Not Reset 41602 Event record Reset UINT16 0x00FF = Reset Request 0x0000 = Not Reset 41603 Total and Fault Trip Counter Reset UINT16 0x00FF = Reset Request 0x0000 = Not Reset...

  • Page 40: Event Record Section

    Event Record section Address Attribute Measurement Format Descriptions Event record information 42021 Full flag of 600 Event record UINT16 0x00FF = Full 0x0000 = Not Full 42022 Last record number UINT16 42023- All Event record Reset Date UINT32 Refer to “Value Table T1” 42024 42025- All Event record Reset Time...

  • Page 41: Captured (Event) Waveform Section

    Captured (Event) Waveform section † Address Attribute Measurement Format Descriptions Captured Waveform information 42101 Number of Captured Waveform UINT16 0 - 4 42102 Event record number of Captured UINT16 1 - 600 Waveform 42103 Reserved UINT16 42104 Reserved UINT16 Captured Waveform Number selector 42105 Selected Waveform number UINT16...

  • Page 42: Auxiliary Function 1 Setup Section

    Auxiliary Function 1 Setup section Address Attribute Measurement Format Descriptions Clock 43001- New Date UINT32 Refer to “Value Table T1” 43002 43003- New Time UINT32 Refer to “Value Table T2” 43004 43005 Clock Save Request UINT16 0x00FF = Save Request (Save Address : 43001 - 43004) 0x0000 = Do not save 43006...

  • Page 43: Auxiliary Function 2 Setup Section

    Auxiliary Function 2 Setup section Address Attribute Measurement Format Descriptions PT Failure Detection Function 43031 PT Failure Function UINT16 0x0000 = Disable 0x0001 = Control 0x0002 = Control & Alarm 43032 PT Failure Aux. Relay UINT16 Refer to “Value Table T10” 43033 PT Failure Time Delay UINT16...

  • Page 44: Digital Input Setup Section

    Digital Input Setup section Address Attribute Measurement Format Descriptions 43051 DI delay time S1 UINT16 0.1 - 10.0 / 0.1 sec Reserved UINT16 43052 43053 Alarm Reset UINT16 Refer to “Value Table T11” 43054 Fault Reset UINT16 Refer to “Value Table T11” 43055 UVR Restoration Control UINT16...

  • Page 45: Digital Output Setup Section

    Digital Output Setup section Address Attribute Measurement Format Descriptions 43071 CB Operation Delay Time UINT16 1 - 10 / 1 sec 43072 CB Open, Close Seal In Time S1 UINT16 0.0 - 3.0 / 0.1 sec 43073 Alarm Output Type UINT16 Refer to “Value Table T12”...

  • Page 46: Do-Relay Interconnection Section 1

    DO-Relay Interconnection section 1 Address Attribute Measurement Format Descriptions 43101 OCR Interconnection UINT16 Refer to “Value Table T10” 43102 OCGR1 Interconnection UINT16 Refer to “Value Table T10” 43103 OVR Interconnection UINT16 Refer to “Value Table T10” 43104 UVR Interconnection UINT16 Refer to “Value Table T10”...

  • Page 47: Di-Do Interconnection Section

    DI-DO Interconnection section Address Attribute Measurement Format Descriptions 43121 DI1 Interconnection UINT16 Refer to “Value Table T10” 43122 DI1 Input Type UINT16 Refer to “Value Table T7” 43123 DI2 Interconnection UINT16 Refer to “Value Table T10” 43124 DI2 Input Type UINT16 Refer to “Value Table T7”...

  • Page 48: Ocr Section

    OCR section Address Attribute Measurement Format Descriptions Inverse OCR 43201 Function UINT16 Refer to “Value Table T9” 43202 Selected Curve UINT16 Refer to “Value Table T3” 43203 Tap (Pickup value) S2 UINT16 0.50 - 12.00 / 0.01 A 43204 Level (Multiplier) S2 UINT16 0.05 - 1.20 / 0.01 Definite time[Instantaneous] OCR...

  • Page 49: Ocgr Section

    OCGR section Address Attribute Measurement Format Descriptions Inverse OCGR 43221 Function UINT16 Refer to “Value Table T9” 43222 Selected Curve UINT16 Refer to “Value Table T13” 43223 Tap (Pickup value) S2 UINT16 0.10 - 2.50 / 0.01 A 43224 Level (Multiplier) S2 UINT16 0.05 - 1.20 / 0.01 Definite time OCGR...

  • Page 50: Uvr Section

    UVR section Address Attribute Measurement Format Descriptions Definite time UVR 43261 Function UINT16 Refer to “Value Table T9” 43262 Tap (Pickup value) UINT16 20 - 220 / 1 V 43263 Delay S2 UINT16 0.03 - 60.00 / 0.01 sec 43264 Reset Time Delay UINT16 1 - 600 / 1 sec...

  • Page 51: Nsovr Section

    NSOVR section Address Attribute Measurement Format Descriptions Definite time NSOVR 43291 Function UINT16 Refer to “Value Table T9” 43292 Tap (Pickup value) UINT16 5 - 110 / 1V 43293 Delay S2 UINT16 0.05 - 60.00 / 0.01 sec 43294 Phase Rotation UNIT16 0 : ABC 1 : ACB...

  • Page 52: Sgr Section

    SGR section Address Attribute Measurement Format Descriptions Definite time SGR1 43321 Function UINT16 Refer to “Value Table T9” 43322 Tap (Pickup value) S1 UINT16 0.2 - 10.0 / 0.1 mA 0 - 359 / 1 ° 43323 UINT16 43324 Delay S2 UINT16 0.05 - 60.00 / 0.01 sec 43325...

  • Page 53: Motor Protection Section

    MOTOR Protection Section Address Attribute Value Format Descriptions THR[49] 43341 Function UINT 16 Refer to “Value Table T9” 43342 0.50 – 15.00 / 0.01 A S2 UINT16 Rated Motor Current [Im] 43343 1.00 – 1.50 / 0.01 S2 UINT16 Constant k Heat Rise Time Constant τ...

  • Page 54: Short-Form Data Block Section

    Short-form Data Block Section A short-form data block is a simplified map consisting of essential registers[including basic measurement and control] needed for users. When acquiring data, multiple polling processes can drop communication speed. However, short-form data block enables users to acquire various basic information through a single polling process, helping to improve communication speed.
  • Page 55 49039- kVA b FLOAT Refer to “Data 49040 Formats” 49041- kVA c FLOAT Refer to “Data 49042 Formats” 49043- Total kVA FLOAT Refer to “Data 49044 Formats” 49045 PF a INT16 x0.001 49046 PF b INT16 x0.001 49047 PF c INT16 x0.001 49048...
  • Page 56 49068 Digital Output channel 7 UINT16 0x0001 = On 0x0000 = Off 49069 Digital Output channel 8 UINT16 0x0001 = On 0x0000 = Off 49070 Digital Output channel 9 UINT16 0x0001 = On 0x0000 = Off 49071 Digital Output channel 10 UINT16 0x0001 = On 0x0000 = Off...
  • Page 57 Bit 4  Def. OCGR (Definite time OCGR) Bit 5  Inst. OCGR (Instantaneous OCGR) Bit 6  Def. OVR (Definite time OVR) Bit 7  Inst. OVR (Instantaneous OVR) Bit 8  Def. UVR (Definite time UVR) Bit 9  Inst. UVR (Instantaneous UVR) Bit 10 ...
  • Page 58 Bit 2  Def. UVR3 (Definite time UVR3) Bit 3  Inv. NSOCR (Inverse NSOCR) Bit 4  Inst. NSOCR (Instantaneous NSOCR) Bit 5  THR (Inverse THR) Bit 6  51LR (Definite time 51LR) Bit 7  Starting motor (Inverse 48) Bit 8 ...

  • Page 59: Value Table

    Value Table T1 : Date † (UINT32) Value Bits to Use Descriptions 16 bits Year (YYYY / xx / xx) 0xFFFF bit15 – bit0 2000 to 2200 in step of 1 16 bits Month / Day (xxxx / MM / DD ) 0xFF00 bit15 –...
  • Page 60 Total and Fault Trip Counter Reset All Record Reset Fault Reset Pickup/Trip/Alarm/Dropout Event Types 0x0F00 Bit.[11:8] Phases Phases A Phases B Phases C Phases G 0x00FF Bit.[7:0] Causes of Events Inverse OCR Instantaneous, Definite time OCR (In F/W Version 5.0 or lower, it is Definite time OCR) Reserved (In F/W Version 5.0 or lower, it is Instantaneous OCR) Inverse OCGR Definite time OCGR...
  • Page 61 DI 1 (Digital Input 1) DI 2 (Digital Input 2) DI 3 (Digital Input 3) DI 4 (Digital Input 4) DI 5 (Digital Input 5) DI 6 (Digital Input 6) DI 7 (Digital Input 7) DI 8 (Digital Input 8) DI 9 (Digital Input 9) DI 10 (Digital Input 10) Alarm Reset Input...

  • Page 62: T4 : Interlock Function Setup

    Link settings between the DI-DO are changed † Event Type consists of a combination of bits. If the hexadecimal value is 0x3101, it indicates Bit.[15:12] = 3 (Trip), Bit.[11:8] = 1 (Phase A), Bit.[7:0] = 01 (Inverse OCR). In other words, the type of the event is “A phase trip by Inverse OCR”. ‡...

  • Page 63: T11 : Digital Input Setup

    T11 : Digital Input Setup Value Descriptions 0x0000 None 0x0001 DIN 1 0x0002 DIN 2 0x0003 DIN 3 0x0004 DIN 4 0x0005 DIN 5 0x0006 DIN 6 0x0007 DIN 7 0x0008 DIN 8 0x0009 DIN 9 0x0010 DIN 10 T12 : DOUT Relay Type Setup Value Descriptions 0x0000...

  • Page 64: T15 : Captured Waveform Data Scale (Int16)

    Bit 11 = High[1] Definite time OVGR[64G] Bit 12 = High[1] Instantaneous OVGR[64G] Bit 13 = High[1] Definite time SGR[67G] Bit 14 = High[1] Definite time SGR2[67G] Bit 15 = High[1] Definite time GR T15 : Captured Waveform Data Scale †...

  • Page 65: Data Formats

    Data formats Accura 7500 supports the following data formats. UINT16: 16bit unsigned integer It is a register value ranging from 0 to 65535. INT16: 16bit signed integer It is a register value ranging from -32768 to 32767. UINT32 or INT32 32 bits are divided into two consecutive 16-bit registers.
  • Page 66 S1 UINT16 or S1 INT16 : UINT16, INT16 with scale [x0.1] Same as UINT16 or INT16, except that it has a scale. S1 represents the scale, and the real value is calculated by multiplying it by 0.1. It is the same as the fixed scale [x0.1]. Real measured value = Measured value x S1(0.1) Example) If OCR Inverse Tap register address [43203] = 10, data format is S1, Real OCR Inverse Tap = 10 x 0.1= 1A...
  • Page 67 FLOAT: 32bit Floating point[IEEE 754] 32 bits are divided into two consecutive 16-bit registers. The first and second registers are the upper and lower registers. The formula for converting to a floating point value is as follows. − × onent −...

  • Page 68: Measurement Value Calculation

    Measurement Value Calculation Fixed Scale x0.1, x0.01, x0.001 The real value is the value measured by multiplying it by the fixed scale [x0.1, x0.01, x0.001]. Real measured value = Measured value x Fixed scale Example) If Frequency register address [40141] = 600, Fixed scale = x0.1, Real Frequency = 600 x 0.1= 60.0 Variable Scale VSA[Scale register address]...
  • Page 69 VSB[Scale register address] VSB is Variable Scale Type B. The real value is the value measured by multiplying it by the variable scale value, and x0.001. Variable scale value indicates one of the values: 1, 10, 100, 1000. Real measured value = Measured value x Variable scale value x 0.001 Example) Scale Address...

  • Page 70: Appendix A Crc-16 Calculation

    APPENDIX A CRC-16 Calculation CRC-16 Generation Modbus RTU Protocol uses the Reverse CRC Generation algorithm. CRC Generation procedure Refer to “Appendix B” for details on the C code. Load a 16-bit register with FFFF hex(all 1’s). Call this the CRC register. Exclusive OR the first 8-bit byte of the message with the low-order byte of the 16-bit CRC register, putting the result in the CRC register.
  • Page 71 CRC table 0000 c0c1 c181 0140 c301 03c0 0280 c241 c601 06c0 0780 c741 0500 c5c1 c481 0440 cc01 0cc0 0d80 cd41 0f00 cfc1 ce81 0e40 0a00 cac1 cb81 0b40 c901 09c0 0880 c841 d801 18c0 1980 d941 1b00 dbc1 da81 1a40 1e00...

  • Page 72: Appendix B Modbus Rtu C Code Example

    APPENDIX B Modbus RTU C Code Example Data Reception and CRC Generation & Checking This is a simple C code example for packet generation and the checking of Modbus RTU Protocol. Request Packet Generation Main module, Read Holding Registers Request Example #define CRC_16 0xA001 unsigned int Crc Table[256];...

  • Page 73: Checking Response Packets

    Checking Response Packets Main module, Read Holding Registers Response Example #define PacketLen int status;  receive_byte is received data buffer unsigned char receive_byte[PacketLen];  received data size is 9 Bytes status =CheckCrc(receive_byte ,PacketLen);  If( status == 0 ) “CRC Successful” Else “CRC Error”...
  • Page 74 void MakeCrcTable( unsigned int Polynomial ) unsigned int ccc; for( ccc=0; ccc<256; ccc++ ) CrcTable[ccc] = GenCrc( ccc, Polynomial, 0 ); unsigned int MakeCrc(unsigned char *buff, unsigned int CrcCount) unsigned int crc; crc = CRC16(buff, CrcCount); return crc; unsigned short CRC16( unsigned char *puchMsg, unsigned short usDataLen ) unsigned char uchCRCHi = 0xFF;...
  • Page 76 Accura 2300/2350, Accura 2300S/2350, Accura 2700/2750, Accura 3000, Accura 3300S/3300, Accura 3300E, Accura 3500S/3500, Accura 3550S/3550, Accura 3700, Accura 5500, and Accura 7500 are trademarks of Rootech Inc. Contact us for detailed product specifications and ordering information. Information contained herein is subject to change without...

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