SMR2 Modbus User Manual

Transcription

1 DEH41181 Rev01 g SMR2 Modbus User Manual

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3 Table of Contents Introduction...2 RTU Transmission Mode... 2 Message frame... 2 RTU Mode Message Frames... 2 Message Format... 2 Electrical Interface...2 Communication Environment...3 Register Map...2 Fixed Value Registers... 2 Dynamic Value Registers... 7 Interpretation of SOS values... 9 Setpoint Registers... 9 Event Registers Interpretation of Event s Bit position in Bit map i

4 Introduction The SMR2 trip unit has an optional communications module that facilitates monitoring of the trip unit via a master Modbus device. Monitoring features include breaker settings and the breaker status. Communication with the SMR2 trip unit requires a FAMECM module powered externally that provides isolation and protection. The Modbus communication protocol is a single master multi-slave protocol that is hardware independent and it interfaces with a 2-wire RS485 interface. A single master device initiates and controls all communication with the other slave devices on the network. A computer with a serial port and an external RS-232/RS-485 converter can be used as the mastermonitoring device. The SMR II trip unit is always the slave and cannot initiate communication. The maximum number of devices on a Modbus network is 32, i.e. only 31 slave devices can be connected to a master. MODBUS devices usually include a Register Map. MODBUS functions operate on Register map registers to monitor, configure, and control module I/O. You should refer to the Register map for your device to gain a better understanding of its operation. The transmission mode defines the bit contents of the message bytes transmitted along the network, and how the message information is to be packed into the message stream and decoded. Standard MODBUS networks employ one of two types of transmission modes: i) ASCII Mode ii) RTU Mode The mode of transmission is usually selected along with other serial port communication parameters (baud rate, parity, etc.) as part of the device configuration. RTU Transmission Mode In RTU (Remote Terminal Unit) Mode, each 8-bit message byte contains two 4-bit Hexadecimal characters, and the message is transmitted in a continuous stream. The greater effective character density increases throughput over ASCII mode at the same baud rate. Message frame A message frame is used to mark the beginning and ending point of a message allowing the receiving device to determine which device is being addressed and to know when the message is completed. It also allows partial messages to be detected and errors flagged as a result. A MODBUS message is placed in a message frame by the transmitting device. Each word of this message (including the frame) is also placed in a data frame that appends a start bit, stop bit, and parity bit. In ASCII mode, the word size is 7 bits, while in RTU mode; the word size is 8 bits. Thus, every 8 bits of an RTU message is effectively 11 bits when accounting for the start, stop, and parity bits of the data frame. RTU Mode Message Frames RTU mode messages start with a silent interval of at least 3.5 character times. Implemented as a multiple of character times at the baud rate being used on the network. The first field transmitted is the device address. The allowable characters transmitted for all fields are hexadecimal values 0-9, A-F. A networked device continuously monitors the network, including the silent intervals, and when the first field is received (the address) after a silent interval of at least 3.5 character times, the device decodes it to determine if it is the addressed device. Following the last character transmitted, a similar silent interval of 3.5 character times marks the end of the message and a new message can begin after this interval. The entire message must be transmitted as a continuous stream. If a silent interval of more than 1.5 character times occurs before completion of the frame (not a continuous stream), the receiving device flushes the incomplete message and assumes the next byte will be the address field of a new message. In similar fashion, if a new message begins earlier than 3.5 character times following a previous message, the receiving device assumes it is a continuation of the previous message. This will generate an error, as the value in the final field will not be valid for the combined messages. Message Format The Modbus RTU Protocol is strictly based upon a transaction scheme where a master device generates a query and a slave device replies with a response. Each query and response message transaction consists of the following four parts 2

5 MODBUS ADDRESSES The master device addresses a specific slave device by placing the 8-bit slave address in the address field of the message (RTU Mode). The address field of the message frame contains two characters (in ASCII mode), or 8 binary bits (in RTU Mode). Valid addresses are from When the slave responds, it places its own address in this field of its response to let the master know which slave is responding. MODBUS FUNCTIONS The function code field of the message frame will contain two characters (in ASCII mode), or 8 binary bits (in RTU Mode) that tell the slave what kind of action to take. Valid function codes are from 1-255, but not all codes will apply to a module and some codes are reserved for future use. MODBUS DATA FIELD The data field provides the slave with any additional information required by the slave to complete the action specified by the function code. The data is formed from a multiple of character bytes (a pair of ASCII characters in ASCII Mode), or a multiple of two hex digits in RTU mode, in range 00H-FFH. The data field typically includes register addresses; count values, and written data. If no error occurs, the data field of a response from a slave will return the requested data. If an error occurs, the data field returns an exception code that the master's application software can use to determine the next action to take. The resulting value is compared to the error check field. Transmission errors occur when the calculated checksum is not equal to the Checksum stored in the incoming packet. The receiving device ignores a bad packet. Electrical Interface The electrical interface is 2-wire RS485 where data flow is bi-directional and half duplex. RS-485 lines from the master device should be connected to a FAMECM module, which is powered externally using a VDC power supply. Refer Figure 1 and 2. The following wire types are recommended for network wiring: Belden 3074F Data Tray 600 V industrial twinax 18 AWG (7X26); or Belden V communication cable 24 AWG (7X32); or Alpha V Communication cable 24 AWG (7x32). Shielded wire should always be used to minimize noise. Polarity is important in RS485 communications and each '+' terminal of every device must be connected together for the system to communicate. Error Checking RTU Mode message frames include an error checking method that is based on a Cyclical Redundancy Check (). The error-checking field of a message frame contains a 16-bit value (two 8-bit bytes) that contains the result of a Cyclical Redundancy Check () calculation performed on the message contents. The checksum field lets the receiving device determine if a packet is corrupted with transmission errors. In Modbus RTU mode, a 16-bit Cyclic Redundancy Check (-16) is used. The sending device calculates a 16- bit value, based on every byte in the packet, using the -16 algorithm. The calculated value is inserted in the error check field. The receiving device performs the calculation, without the error check field; on the entire packet it receives. Figure1. Connection between ETU and FAMECM module 2

6 The communication happens at 19200bps with a Modbus address of 100 Figure3. Communication modules used with trip unit Modbus Message Frames Figure2. Connection between Breaker and FAMECM module Communication Environment Master s Query Slave Function Data (n bytes) Start No. of Registers The trip unit is always the slave and cannot initiate communication All the registers are read-only Hardware layer RS485: Data moves serially on a 2-wire differential line (used for TX as well as Rx i.e.; half- duplex) N-8-1, no parity, 1 start bit, 8 data bits & 1 stop bit (10 bits per character) Communication Protocol RTU Modbus Master-Slave protocol Commandresponse (half-duplex) Min delay between messages is 3.5 char time Max delay within message is 1.5 char time. Slave Response time: minimum 3.5 char; maximum 50mS + 1mS per register Register order: MSB first, then LSB In the presence of a communication module on Trip unit A pair of rotary switch decides the Modbus address (0 to 255) A pair of slide switch decides the baud rate (2400, 4800, 9600 or 19200bps). These switches are available on the backside of the module In the absence of a communication module on Trip unit Slave s Response Slave (1byte) Functio n Examples : Number of Bytes Byte1 Data (n bytes) Byte2.. Read Holding Registers (Function 03) Byte n (2bytes) Use this command to read setpoint or fixed value registers. It specifies the starting register and the number of registers to be read. Read the registers from device 100: Slave Addres s (1 byte) Function Data (n bytes) Start (2 bytes) No. of Registers (2 bytes) (2 bytes) 3

7 64h 03h 0Bh C2h 00h 03h l h 64h 05h 00h 04h FFh 00h l h Response: (register contents: 3010 = 022Bh, 3010 = 0000h, 3012 = 0066h) Slave Addres s (1byte) Functio n Numbe r of Bytes (1byte) Byte1 Data (n bytes) Byte h 03h 06h 02h 2Bh 00h 00h 00h 66h Byte n Read Input Registers (Function 04) Use this command to read dynamic value or event registers. Read the registers from device 100: Query: Slave Function Data (n bytes) Start No. Of Registers (2 bytes ) l h 64h 04h 04h 22h 00h 03h l h Response: (register content: 1058 = FFFFh, 1059 = A01Ah, B1h) Slave Addres s Function Number of Bytes Byte1 Data (n bytes) Byte Byte n (1 byte) 64h 04h 06h FFh FFh A0h 1Ah 11h B1h Force Single Coil (Function 05) Use this command to perform remote control. This command sets a single coil to enter ON or OFF. Force coil 4 of device 100 ON (FF00h force on, 0000h force off) Query: Slave Function Data (n bytes) Coil Data (2 bytes) (2 bytes) l h Response: (echo query message) Slave Function Data (n bytes) Coil Data (2 bytes) 64h 05h 00h 04h FFh 00h l h Preset Single Register (Function 06) Use this command to write to a register. This presets a value into a single holding register. Preset register 0002 to hex in slave device 17. Query: Slave Function Data (n bytes) Register No. of Registers 11h 06h 00h 02h 00h 03h l h Response (echo query message) Slave Function Data (n bytes) Register No. of Registers (2 bytes) 11h 06h 00h 02h 00h 03h l h Retransmit Last Message (Function 56) Query: Slave Response Function 64h 38h l h Slave Function Data (n bytes) 4

8 Addres s Previous transmitted data (1 byte) 64h 38h xxh xxh xxh xxh xxh xxh xxh xxh xxh l h Exception Response If the slave receives a message without a communications error, but is unable to process it, the slave will return an exception response to inform the master of the error. The high order bit will be set in the function code and returned with the characterizing exception response code: 01h - Invalid Function The Function is not recognized or defined by the SMR2. 02h - Invalid register The Register address is not recognized or defined by the SMR2 05h Acknowledge The SMR2 has accepted the request and is processing it, but a long duration of time will be required to do so. This response is returned to prevent a timeout error from occurring in the master. SMR2 Modbus User Manual The SMR2 is busy processing a long duration command. The master should retransmit the message latter when the slave is free. 84h - Partial register access error Command reads or writes to a register that represents only part of the SMR2 register address. The multiple register addresses must be read or written together. Example: Long Time SOS consumes 2 register addresses, thus both must be read together. 85h - Write protect violation Command writes to a valid Register, which is defined as Read Only. 88h - Invalid coil The Coil address is not recognized or defined by the SMR2. Function s The Modbus functions listed in below are supported: 06h - Slave busy Function Command Purpose Register Group 03 Read Holding Registers Reading the setpoint registers Setpoint registers, Fixed value registers 04 Read Input Registers Reading actual value registers Actual value registers and event registers 05 Force Single Coil Setting the signal coil or executing single command 06 Preset Single Register Write Data into single Register Command coils Setpoint registers, Fixed value registers hex Preset Multiple Registers Write Data into multiple Registers Setpoint registers, Fixed value registers 56 Retransmit last message Retransmit last message N/A 5

9 Register Map While modbus communication with Target Communication Accessory module, all the registers are read only registers. None of them can be written. But while Modbus communication with Test Kit, most of the Fixed value & Setpoint registers can be read as well as written. Fixed value registers start at 0000 and are read by Function 03. Actual value registers start at 1000 and are read by Function 04. Event registers start at 2000 and are read by Function 04. Setpoint registers start at 3000 and are read by Function 03. Writing to the Coil registers, implement supervisory control through remote commands All registers composed of 16 bit integers, values less than 256 stored in lower byte Fixed Value Registers Fixed value registers address starts at 0000, read by Function 03. Written with Function code 06/16 (decimal) The data stored in these registers are the data stored during trip unit optioning. Register Contents Range Type R/W Format address 0000 Product Id Unsigned Int mode RO ETU Serial Number Unsigned Int high mode -- RO ETU Serial Number Unsigned Int low mode --- RO ETU Date Unsigned Int high mode --- RO ETU Date low Unsigned Int mode --- RO --- Frame Size 1 to 3 Unsigned Int 0005 mode --- RO 1 G G630 3 K 0006 Amp Rating 1 to 13 mode--- RO Unsigned Int 1 7/7 2 25/ / /125 2

10 -- SMR2 Modbus User Manual 5 150/ / / / / / / Information Memory Option Byte 1 Bitmappe d 0 to FFFFh mode--- RO --- b0 Instantaneous 0 enabled 1 disabled b1 Short Time 0 enabled 1 disabled b2 Long Time 0 enabled 1 disabled b3 Watchdog 0 enabled 1 disabled b4 Zone Select Interlock 0 enabled 1 disabled b /400 Hz Operation 0 50/60 Hz Hz b6 Thermal Watchdog 0 disabled 1-99 enabled b7 Unused Software revision number Product revision number 0010 Max Number of events stored 0000 to RO 4 digit BCD to 9999 mode --- RO 4 digit BCD --- Always 8 RO Unsigned Int Example: To find out Phase-A SOS, A Modbus query to read 1002 and 1003 registers need to be sent to SMR2 by the master. Dynamic Value Registers Actual value registers start at 1000, read by Function 04.All the dynamic value registers are 32-bit in length. Hence, query of any variable results in two Modbus register reads, each of 16-bit length. Even numbered register holds upper-16 bits; Odd numbered register holds lower 16 bits There are 32 bits in this data. The upper-16 bits would appear in register 1002 and lower-16 bits in register 1003 as a part of the response. 7

11 LT Accumulators (A, B, C & N) give normalized values and are typically max Hence, they are multiplied with 10,000 and sent out on Modbus for reading purposes. Reg. Contents Range Type Format R/W Number of pending RO Unsigned Int event SOS Current Phase A RO Unsigned Int SOS Current Phase B RO Unsigned Int SOS Current Phase C RO Unsigned Int SOS Current Phase N RO Unsigned Int LT Accumulator A* RO Unsigned Int LT Accumulator B* RO Unsigned Int LT Accumulator C* RO Unsigned Int LT Accumulator N* RO Unsigned Int ST Accumulator RO Unsigned Int GF Accumulator RO Unsigned Int PL Accumulator RO Unsigned Int Breaker Status Note: If system is in pickup corresponding bit is set to 1. Battery status 1 indicates healthy battery. ZSI active is set 1 when ZSI is ACTIVE. When breaker is open AUXS1bit is set to 1. Bitmapped 0 to FFFFh RO B0: Unused B1: ST Pickup B2: GF Pickup B3: PL Pickup B4 (unused) B5: LT 105 Pickup (PU >= 105) B6: LT 95 Pickup (95 <= PU < 105) B7: LT 75 Pickup (75 <= PU < 95) B8: LT 60 Pickup (60 <= PU < 75) B9: LM 1 B10: LM 2 B11: ZSI active B12: Battery Status B13: AUXS1 B14, B15 Unused Push-Button Status 0-1 RO Unsigned Int 1 = Push button is pressed 0 = Push Button is released Measured ETU RO Unsigned Int Temperature ETU Trip Count RO Unsigned int LT Trip Count RO Unsigned int ST Trip Count RO Unsigned int Instantaneous Trip RO Unsigned int Count GF Trip Count RO Unsigned int PL Trip Count RO Unsigned int Software Fault Trip RO Unsigned int Count Remote Trip Count RO Unsigned int RP Missing Trip Count RO Unsigned int Flash Erased Count RO Unsigned int No module Trip Count RO Unsigned int Over temperature Trip Count RO Unsigned int 8

12 Interpretation of SOS values The Sum Of Squares values (SOS) of a phase is a measure of the RMS value of current flowing through that Phase.SMR2 calculates this values in every half cycle and use this value as a measure of current to perform the protection algorithm. The no. of current samples used for SOS calculation depends on the frequency. When a current equal to sensor rating (I CT ) value is flowing through the breaker, a SOS value of will be displayed if supply frequency is 50 Hz. For 60 Hz, This value will be I CT _SOS_Value for 50 Hz = I CT _SOS_Value for 60 Hz = Using this value we can calculate SOS value for any current or current for any given SOS value. For given current, SOS value can be calculated using the following equation: SOS value = (input current/sensor rating) 2 x I CT _SOS_Value For given SOS value,current amplitude can be calculated using the following equation: Input current = (SOS Value / I CT _SOS_Value) 0.5 x Sensor Rating Example: Current to SOS conversion sensor rating = 400A Input current=500a Frequency =50Hz select I CT _SOS_Value based on frequency SOS value = (input current/sensor rating) 2 x I CT _SOS_Value = (500/400) 2 x = For 500A, 50Hz input current SOS value will be equal to Example: SOS to current conversion Sensor rating = 400A SOS Value= Frequency =50Hz Select I CT _SOS_Value based on frequency Input current = (SOS Value / I CT _SOS_Value) 0.5 x Sensor Rating = ( /830304) 0.5 x 400 = 1200 A If SOS Value= for 50 Hz, then corresponding current is 1200A Note: UL/IEC bit (Bit 0) in Control Byte (Modbus 3012) is monitored and ETUs operating frequency is determined based on this bit. UL/IEC bit (Bit 0) in Control byte Line Frequency 0 - UL 60 Hz 1 - IEC 50 Hz Setpoint Registers Setpoint registers start at 3000, read by Function 03 Reg. Contents Range Type R/W Format 3000 Hour Minute Unsigned int (Unused) Unsigned int (Unused)

13 3002 Seconds Long Time Pickup 0-15 Mode--RO 3004 Long Time delay 0-6 Mode--RO 3005 Short time pickup 0-9 Mode--RO Unsigned int (Unused) Unsigned int Unsigned int 0 Line Line Line 5 3. Line Motor Motor Unsigned int Short Time delay 0-9 Mode--RO 3007 Ground Fault pickup 0-8 (in GF module 0-9 (in GFA module) Mode--RO Value second I 2 T 0 40ms No 1 120ms No 2 210ms No 3 310ms No 4 420ms No 5 420ms Yes 6 310ms Yes 7 210ms Yes 8 120ms Yes 9 40ms Yes Unsigned int 0 0.2X 1 0.3X 2 0.4X 3 0.5X 4 0.6X 5 0.7X 6 0.8X 7 0.9X 8 1.0X 10

14 3008 Ground Fault delay 0-9 Mode RO 3009 Inst. Pickup 0-9 Mode--RO SMR2 Modbus User Manual 9 GFA Reset (In GFA module only) Value second I 2 T 0 40ms No 1 120ms No 2 210ms No 3 310ms No 4 420ms No 5 420ms Yes 6 310ms Yes 7 210ms Yes 8 120ms Yes 9 40ms Yes Unsigned int Refer to the table 3010 Module Last Trip Data Bitmap Control Byte Bitmap Mode - RO Mode--RO Mode--RO 3013 Protection Multiplier Mode --RO 3014 Neutral Protection Mode RO 3015 Temperature Limit degree C 3016 Product Reject Key RO 3017 Rating Plug Serial Number RO high 3018 Rating Plug Serial Number low Mode RO % 100% 0%, 50%, 100% 11

15 3019 Rating Plug Date high Rating Plug Date low Rating Plug LT Settings Number of Data bits Number of Stop bits Parity Baud Rate 0-3 mode RO mode RO mode RO 0 7-bits 1 8-bits 0 1-stop bit 1 2-stop bits 0 No parity 1 Even Parity 2 Odd Parity Modbus LM1 Pickup 0-9 mode - RO 3028 LM2 Pickup 0-9 mode - RO ETU is known by this slave address in the communication network and communicates over this address

16 3029 Flag Cleared Byte 00 & 0xFF 3030 Test Kit Modbus Test Kit Baud Rate 0-3 mode RO 3032 Ammeter Display Current Ammeter Display Current Pushbutton SMR2 Modbus User Manual 00 Cleared (trip history can not be shown on Flag Module LEDs) 0xFFFF Not Cleared (trip history can be shown on Flag Module LEDs) This is to test COMM switches. This returns the cumulative Modbus address set through two COMM switches This is to test DIP switches. This holds the value which is displayed on LCD display Value greater than 9999 will be displayed as ---- Alternate value, which can be written while testing Ammeter module. As long as Select_Phase is pushed, this value gets displayed. Value greater than 9999 will be displayed as ---- the newest. An event is automatically cleared once read by the host. Event Registers The trip unit stores up to eight events, with each event utilizing 8 registers to describe the details of the event. Last eight events are stored in chronological order, with EVENT 1 being the oldest event and EVENT n being 13

17 Reg Contents Units/ Type Format Range R/W 2000 Event Event RO Unsigned int 2001 Hour 0 RO Unsigned int 2002 Minute 0 RO Unsigned int 2003 Second 0 RO Unsigned int 2004 Milliseconds 0 RO Unsigned int 2005 Event specific data RO Unsigned int 2006 Event specific data RO Unsigned int 2007 Event specific data RO Unsigned int 2008 Event code Event RO Unsigned int 2009 Hour 0 RO Unsigned int 2010 Minute 0 RO Unsigned int 2011 Second 0 RO Unsigned int 2012 Milliseconds 0 RO Unsigned int 2013 Event specific data RO Unsigned int 2014 Event specific data RO Unsigned int 2015 Event specific data RO Unsigned int 2056 Event code Event RO Unsigned int 2057 Hour 0 RO Unsigned int 2058 Minute 0 RO Unsigned int 2059 Second 0 RO Unsigned int 2060 Milliseconds 0 RO Unsigned int 2061 Event specific data RO Unsigned int 2062 Event specific data RO Unsigned int 2063 Event specific data RO Unsigned int If another event occurs before the master reads all the existing events, the oldest event is lost, new event data will be placed in the EVENT 8 register, and the older event register contents are shifted. The total number of events since the last reset will be kept counted at register location Events are read using Function

18 Interpretation of Event s The following table describes the meaning of each event code Event (Hex ) 1 Long Time Overcurrent Trip Meaning Register 1 Register 2 Register 3 Fault SOS Current SMR2 Modbus User Manual Fault SOS Current 2 Short Time O/C trip Fault SOS Current 3 Instantaneous O/C Instantaneous Trip Fault Current 4 Ground Fault Trip Fault SOS Current 5 Phase Loss Trip Phase Loss Accumulator 6 Remote Trip Bitmap 16-bit 7 Over-Temp Trip Temperature 8 9 A B C Aux Switch Opened Bitmap 16-bit D E Low Trip Voltage Bitmap 16-bit Warning F Software Fault 10 RAM Failure Bitmap 16-bit 11 ROM Failure Bitmap 16-bit Rating Plug Missing Bitmap 16-bit 14 Short Time Switch Bitmap 16-bit Change 15 Long Time Switch Bitmap 16-bit Change 16 Instant Switch change Bitmap 16-bit 17 Module Switch/Type Bitmap 16-bit Change 18 Short Time Delay Bitmap 16-bit Switch Change 19 Long Time Delay Bitmap 16-bit Switch Change 1A Module Missing Trip Fault SOS Current Instantaneous Fault Current Fault SOS Current Phase Loss Accumulator 15

19 Bit position in Bit map Bit Position in Bitmap Meaning Event code (Hex) 0 0 No Remote Trip 6 1 Remote Trip 1 0 Aux Switch Open C 1 Aux Switch Closed 2 0 No Low Trip Voltage Warning 0E 1 Low Trip Voltage Warning 3 0 No RAM Failure 10 1 RAM Failure 4 0 No ROM Failure 11 1 ROM Failure 5 0 No Rating Plug Missing 13 1 Rating Plug Missing 6 0 No Short Time Switch Change 14 1 Short Time Switch Change 7 0 No Long Time Switch Change 15 1 Long Time Switch Change 8 0 No Instant Switch change 16 1 Instant Switch change 9 0 No Module Switch/Type Change 17 1 Module Switch/Type Change 10 0 No Short Time Delay Switch Change 18 1 Short Time Delay Switch Change 11 0 No Long Time Delay Switch Change 19 1 Long Time Delay Switch Change 12 0 No Missing Module 12 1 Missing Module 16

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21 g DEH41181 Rev01 General Electric Company 41 Woodford Ave., Plainville, CT General Electric Company GE Consumer & Industrial 17