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User Manual
MODBUS Communication For
XVG/eXVG Gas Fuel Metering Valves
SD-6021 Rev 1
September 2008
Precision Engine Controls Corporation claims proprietary rights to the information disclosed herein. This document is furnished in
confidence on the express understanding that neither it nor any reproduction thereof will be disclosed to others or used for the purpose
of manufacture or procurement.
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PREFACE The purpose of this manual is to enable users to: Understand the basics of XVG/eXVG Modbus communications via standard definitions, interfaces, and protocols. Setup Modbus communication with a network of one or more XVG/eXVGs. It is expected that the user have sufficient knowledge of serial communication and Modbus protocol. This manual only mentions the relevant information regarding XVG/eXVG and Modbus, but every attempt has been made to provide sufficient inf
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Table of Contents PREFACE........................................................................................................................ 2 Table of Contents................................................................................................................ 3 1 Serial Communication ................................................................................................ 4 2 Baud Rate............................................................................
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1 Serial Communication The primary interface used for XVG/eXVG is serial communication, which is the exchange of data one-bit-at-a time, sequentially, on a single data line or channel. XVG/eXVG can communicate either in PECC (a propriety standard protocol) or Modbus protocol via the serial interface. 2 Baud Rate Baud rate is the speed at which a data line changes its state or the number of times per second the line changes state. If two serial devices are connected together
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Follow RS232 and RS485 standards for wiring and biasing of the communication bus. 6 XVG/eXVG Modbus Communication Default Settings The default settings for XVG/eXVG Modbus communication are as follows: - Baud Rate: 19200 - Parity Mode: Even - Number of Start Bits: 1 - Number of Stop Bits: 1 - Device Address: 1 7 Protocol Modbus devices communicate using a master/slave technique, in which only one device (the master) can initiate transactions. The other device (the
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7.2 Modbus Transactions The slave’s response message is also constructed using Modbus protocol. It contains fields confirming the action taken, any data to be returned, and an error– checking field. If an error occurred in receipt of the message, or if the slave is unable to perform the requested action, the slave will construct an error message and send it as its response. Request FUNCTION CODE + REQUEST DATA Response, no error FUNCTION CODE + RESPONSE DATA Response, wit
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7.4 Modbus Functions The following Modbus functions are supported by the XVG/eXVG: - Read Registers (0x03) - Write Single Register (0x06) - Write Multiple Registers (0x10) - Diagnostics (0x08) Query Data sub-function (0x00) The master can address individual slaves, or can initiate a broadcast message (using device address 0) to all slaves. Slaves perform the actions requested by the broadcast messages but will not return a response. Per Modbus protocol, only Write Single Re
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Example: Request to read holding registers 108 - 110 Request Response 01 03 00 6B 00 03 74 17 01 03 06 02 2B 00 00 00 64 05 7A Slave Address 01 Slave Address 01 Function 03 Function 03 Starting Address Hi 00 Byte Count 06 Starting Address Lo 6B Register Value Hi (108) 02 Number of Registers Hi 00 Register Value Lo (108) 2B Number of Registers Lo 03 Register Value Hi (109) 00 CRC 7417 Register Value Lo (109) 00 Register Value Hi (110) 00 Register Value Lo (110) 64
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Example: Request to write 0x03 to register 2. Request Response 01 06 00 01 00 03 98 0B 01 06 00 01 00 03 98 0B Function 06 Function 06 Register Address Hi 00 Register Address Hi 00 Register Address Lo 01 Register Address Lo 01 Register Value Hi 00 Register Value Hi 00 Register Value Lo 03 Register Value Lo 03 CRC 98 0B CRC 98 0B Table 9: Modbus Function 06 – Example 7.4.3 Write Multiple Registers (0x10) Request message: SLAVE ADDRESS + FUNCTION CODE + STARTING AD
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Starting Address Hi 00 Starting Address Hi 00 Starting Address Lo 01 Starting Address Lo 01 Quantity of Registers Hi 00 Quantity of Registers Hi 00 Quantity of Registers Lo 02 Quantity of Registers Lo 02 Byte Count 04 CRC 1008 Registers Value Hi 00 Registers Value Lo 0A Registers Value Hi 01 Registers Value Lo 02 CRC 9230 Table 12: Modbus Function 16 – Example 7.4.4 Diagnostics (0x08) (Loopback) Request & Response message: SLAVE ADDRESS + FUNCTION CODE + SUB-FUN
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8.1 RS-232 Connection (for XVG/eXVG with RS-232 interface) PC COM Port Wire Color (DB9M Connector) (If XVG/eXVG is XVG/eXVG Terminal Block supplied with optional harness) Signal Pin # Signal Pin # SERIAL RX 2 SERIAL TX 39 WHT/ORN/BLU SERIAL TX 3 SERIAL RX 40 WHT/ORN/YEL WHT/ORN/GRN SERIAL RTN 5 SERIAL RTN 41 Table 14: RS-232 Interface Connection 8.2 RS-485 Connection (for XVG/eXVG with RS-485 interface) PC COM Port Wire Color XVG/eXVG Terminal Through RS232- (If XVG/e
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9.1.1 General Setup Parameters Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value Operating Mode: 0=Stroke, 1=Flow 3500 IDM_MODE W2 Measurement, 2=Flow Control, 3=Flow U16 0 Limiting Bit15=Don’t care, Bit14 = inter-character 3501 IDM_PROTOCOL W2 timeout enable for Modbus, other bits U16 0 reserved 3502 IDM_DEMANDSRC W4 Demand Source, not used U16 0 Digital Command Enable: Bit0, 0=Analog, 3503 IDM_DIGCMDEN W4 U16 0 1=Digital, other bits reser
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Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value Flow Control Enable: 0=Baseline (Stroke 3521 IDM_FLOWCTRLEN W4 U16 1 Mode) Valve, 1=FM / FC / FL valve Current fault persist time: x20mS, range 0- 3522 IDM_FLTTMCURRENT W4 U16 32767 32767 Over temperature shutdown fault persist time: 3523 IDM_FLTTMTMPSHUT W4 U16 500 x20mS, range 0-32767 3524 IDM_SOLIMAX W4 Solenoid Current Limit: range 1-4095 U16 3500 Analog Output Zero Configuration: 0=Disa
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Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value 3541 IDM_PARITY W2 Modbus parity: 0 = None, 1 = Odd, 2 = Even U16 0 Modbus receive message timeout: 0 = auto- scale to 3.5 character times for current baud 3542 IDM_RXMSGTMOUT W2 U16 0 rate. Other values: n * 0.1ms timeout. Range: 0 to 1000. 3543 IDM_MODELNO[0] W4 X 3544 IDM_MODELNO[1] W4 V 3545 IDM_MODELNO[2] W4 G 3546 IDM_MODELNO[3] W4 3547 IDM_MODELNO[4] W4 Model Number: null terminated
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Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value 5508 5509 IDM_SETUPCHECK W4 Setup parameter checksum U32 12345 Faults to Shutdown on, same as 5510 5511 IDM_SHUTDNFLTS W4 U32 0 IDM_FAULTFLAGS Fault output configuration bit-field, to configure which fault codes will show on 5512 5513 IDM_FAULTOUTCFGL W4 U32 0 digital output channel 0. Same bits as IDM_FAULTFLAGSL Thermal age threshold for Electronics Age 5514 5515 IDM_TAT W4 Warning fault, unit
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Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value Input Pressure Sensor Offset: range -10 – 10 7578 7579 IDM_INPRESOFF W4 Float 0 PSIA 7580 7581 IDM_OUTPRESGAIN W4 Output Pressure Sensor Gain: range 1 – 2 Float 1 Output Pressure Sensor Offset: range -10 – 7582 7583 IDM_OUTPRESOFF W4 Float 0 10 PSIA 7584 7585 IDM_TEMPSENSEGAIN W4 Gas Temp Sensor Gain: range 0.1 – 3.0 Float 1 7586 7587 IDM_TEMPSENSEOFF W4 Gas Temp Sensor Offset: -20 – 20 Deg
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Register XVG/eXVG Parameter Write Default Description Type Number Name Access Value 7650 7651 IDM_AO0CUROFF W4 AO0 Current Offset: range -4 to 4 counts Float 0 7652 7653 IDM_AO0VOLTGAIN W4 AO0 Voltage Gain: range 0.72 – 0.80 Float 1 7654 7655 IDM_AO0VOLTOFF W4 AO0 Voltage Offset: range -4 to 4 counts Float 0 7656 7657 IDM_AO1CURGAIN W4 AO1 Current Gain: range 0.72 – 0.80 Float 1 7658 7659 IDM_AO1CUROFF W4 AO1 Current Offset: range -4 to 4 counts Float 0 7660 7661 IDM_AO1VOLTGAI
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The position interpolation feature is enabled / disabled via the IDM_POSINTTBLEN setup parameter. The valve will ignore this data in this table and assume a linear stroke profile when IDM_POSINTTBLEN is disabled. Valid Parameter Interpolation Table values are in the range of 683.0-3413.0, values are in fixed point IQ8 format (count value 8 multiplied by 2 ). Pre- Register XVG/eXVG Parameter Write Corresponding Demand Type Cal Number Name Access Default 5600 5601 IDM_POSTBL0 W2
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Pre- Register XVG/eXVG Parameter Write Corresponding Demand Type Cal Number Name Access Default 5670 5671 IDM_POSTBL35 W2 Counts: 2218.6250, 13.0mA Demand U32 567968 5672 5673 IDM_POSTBL36 W2 Counts: 2389.2500, 14.0mA Demand U32 611648 5674 5675 IDM_POSTBL37 W2 Counts: 2559.8750, 15.0mA Demand U32 655328 5676 5677 IDM_POSTBL38 W2 Counts: 2730.5000, 16.0mA Demand U32 699008 5678 5679 IDM_POSTBL39 W2 Counts: 2901.1250, 17.0mA Demand U32 742688 5680 5681 IDM_POSTBL40 W2 Counts: 3071.
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Register XVG/eXVG Parameter Write Default Corresponding Pressure Ratio Type Number Name Access Value 5950 5951 IDM_PRTBL0 W4 0.1 U32 1677722 5952 5953 IDM_PRTBL1 W4 0.2 U32 3355443 5954 5955 IDM_PRTBL2 W4 0.3 U32 5033165 5956 5957 IDM_PRTBL3 W4 0.4 U32 6710886 5958 5959 IDM_PRTBL4 W4 0.5 U32 8388608 5960 5961 IDM_PRTBL5 W4 0.6 U32 10066330 5962 5963 IDM_PRTBL6 W4 0.7 U32 11744051 5964 5965 IDM_PRTBL7 W4 0.8 U32 13421773 5966 5967 IDM_PRTBL8 W4 0.9 U32 15099494 5968 5969 IDM_
