GE Infrastructure Sensing - GE Measurement & Control
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1. See Table 1 below for a description of the options available at the above prompt Table 1 UART Bits Options Option Bar Data Bits Stop Bits COMM PROGRAM The Network ID number is used UART bits by the IDM software only Enter current setting appears here a Network ID number between 1 and 254 and then press ENT Network D The default ID number is 1 current number appears here Note Jfmore than one meter is connected to a network each meter must have a unique Network I D 913 299A 3 of 9 January 2005 Setting Up MODBUS Communications cont MODBUS Register Map COMM PROGRAM Network D current number appears here MODBUS BAUD RATE current value appears here Z RE Ee COMM PROGRAM MODBUS BAUD RATE current value appears here MODBUS PARITY current setting appears here none l odd l even l COMM PROGRAM MODBUS PARITY current setting appears here MODBUS STOP BITS current setting appears here COMM PROGRAM MODBUS STOP BITS current setting appears here MODBUS Address current address appears here Press the appropriate Fx function key to select 2400 4800 or 9600 for the MODBUS baud rate Press the appropriate Fx function key to select NONE ODD or EVEN for the MODBUS parity setting Press the appropriate Fx function key to select 1 or 2 for the MODBUS stop bits setting Enter a MODBUS Address number between 1 and 2472. 913 299A Sensing January 2005 MODBUS Communications for the GC868 Introduction Your Model GC868 hardware and software GC3E MBS have been modified to provide improved MODBUS communications The MODBUS option card 703 1358 provides an RS485 interface with a host system while the main circuit board continues to support RS232 communications for use with a PC running PanaView software To properly set up the instrument use this addendum along with the standard GC868 flowmeter User s Manual 910 226 This document shows how to install the MODBUS option card and how to program the modified GC868 to access this special feature When equipped with the optional MODBUS output card the GC868 flow transmitter can send flow data and diagnostic information to a flow computer or SCADA serially using a Gould type RTU protocol In this case only the MODBUS function command 3 read multiple registers 6 write multiple registers is valid The format for the data exchange is as follows The send command initiated by the host flow computer or controller comes in the form time delimiter lt Addr gt lt 3 gt lt First Register MSB gt lt First Register LSB gt lt Register Count MSB gt lt Register Count LSB gt lt CRC Low gt lt CRC High gt time delimiter The response initiated by the host flow computer or controller comes in the form time delimiter lt Addr gt lt 3 gt lt Byte count gt lt Data
3. gt lt CRC Low gt lt CRC High gt time delimiter January 2005 A Introduction cont The format for the returned data types is as follows e Integer 16 bit Integer lt MSB gt lt LSB gt 1 Register 16 bit integer e Integer 32 bit Integerl lt MSB gt lt LSB gt lt LSB gt lt LSB gt 2 Register 32 bit integer Floating Point FP lt EXP gt lt MAN gt lt MAN gt lt MAN gt 2 Registers 32 bit IEEE floating point number Installing the MODBUS IMPORTANT The installation information presented here supersedes Option Card the information in the standard GC868 User s Manual The modified GC868 uses the RS485 standard for MODBUS communications This standard allows up to 32 nodes drivers and receivers on one multidrop network at distances up to 4 000 ft 1 200 m To connect the instrument s to the host system GE Infrastructure Sensing recommends using a 24 gauge 24 AWG twisted pair cable with a characteristic impedance of 120 ohms and a 120 ohm termination at each end of the communications line The MODBUS option card must be plugged into either slot 5 or slot 6 of the GC868 On the option card pin 1 is the TMT inverting or negative connection and pin 2 is the TMT non inverting or positive connection To link the GC868 to the control system connect the two wires of the twisted pair cable from these terminals to the corresponding terminals at the control system Note Iftwo MODBUS option cards are install
4. 9600 7 MODBUS parity 0 none 1 odd 2 even 8 MODBUS stop bits 1 1 stop bit 2 2 stop bits 913 299A 8 of 9 January 2005 A 1 Ch Meter 2 Ch Meter GLOBL i Baud Rate RS232 F4 F1 F2 F3 2400 4800 9600 19200 UART Bits RS232 F3 F4 F1 8even 7 0dd 7even Network I D MODBUS Baud Rate F2 F3 4800 9600 MODBUS Parity F2 F3 ODD EVEN MODBUS Stop Bits F2 2 MODBUS Address NOTE Plain text represents prompt area messages and boxed text represents option bar choices Fx represent function keys to select option bar choices Figure 1 MODBUS Menu Map 913 299A 9 of 9
5. Then press ENT Press EXIT until you return to RUN mode and the screen resumes the display of data measurements Then reboot the meter to load the new settings into memory To request specific parameters from the GC868 via the MODBUS the control system must enter the appropriate register number Only registers 1 through 90 are available for MODBUS communications while registers 508 through 512 are used by the GC868 to store the MODBUS parameters For details see Table 2 on the next page for a 1 Channel meter or Table 3 on page 6 for a 2 Channel meter Note Ifyou request Ch2 or AVE data from a 1 Channel meter the values will all be zero 913 299A 4of9 MODBUS Reg DPR Hex Addr Description Clear Ch1 Totalizers Table 2 MODBUS Registers for a 1 Channel GC868 Scaling decimal places January 2005 Size in Bytes 2 16 bit signed Not Used 2 16 bit signed Velocity 4 2 16 bit int 2Act Volumetric Q DIGITS 4 IEEE 32 bit 2Std Volumetric Q DIGITS 4 IEEE 32 bit 3Fwd Totals T DIGITS 4 2 16 bit int 3Rev Totals T DIGITS 4 2 16 bit int Tot Digits 0 2 2Mass Flow M DIGITS 4 IEEE 32 bit 4Fwd Mass Totals MT DIGITS 4 2 16 bit int 4Rev Mass Totals MT DIGITS 4 2 16 bit int Mass Tot Digits Timer 2 4 2 16 bit int Error Code 2 Sound Speed Density 4 2 16 bit i
6. 4 2 16 bit int Ch1 Sig Strength Downstream 4 2 16 bit int Ch1 Temperature 4 2 16 bit int Ch1 Pressure Ch2 Velocity 4 2 16 bit int 4 2 16 bit int Ch2 Act Volumetric Q DIGITS 4 IEEE 32 bit Ch2 Std Volumetric Q DIGITS 4 IEEE 32 bit Ch2 Fwd Totals T DIGITS 4 2 16 bit int Ch2 Rev Totals T DIGITS 4 2 16 bit int Ch2 Tot Digits 0 2 Ch2 Mass Flow M DIGITS 4 IEEE 32 bit Ch2 Fwd Mass Totals MT DIGITS 4 2 16 bit int Ch2 Rev Mass Totals MT DIGITS 4 2 16 bit int Ch2 Mass Tot Digits 2 Ch2 Timer 4 2 16 bit int Ch2 Error Code Ch2 Sound Speed 2 4 2 16 bit int Ch2 Density 4 2 16 bit int 913 299A Ch2 Sig Strength Upstream 4 2 16 bit int 6 of 9 MODBUS Reg Table 3 MODBUS Registers for a 2 Channel GC868 Continued DPR Hex Addr Description Ch2 Sig Strength Downstream Scaling decimal places January 2005 Size in Bytes 4 2 16 bit int Ch2 Temperature 4 2 16 bit int Ch Pressure 4 2 16 bit int Avg Velocity 4 2 16 bit int Avg Act Volumetric Q DIGITS 4 IEEE 32 bit Avg Std Volumetric Q DIGITS 4 IEEE 32 bit Avg Fwd Totals T DIGITS 4 2 16 bit int Avg Rev Totals T DIGITS 4 2 16 bit int Avg Tot Digits 0 2 Avg Mass Flow M DIGITS 4
7. IEEE 32 bit Avg Fwd Mass Totals MT DIGITS 4 2 16 bit int Avg Rev Mass Totals MT DIGITS 4 2 16 bit int Avg Mass Tot Digits 0 2 Avg Timer 4 2 16 bit int 2 Avg Error Code 2 Avg Sound Speed 4 2 16 bit int CH1 Signal Quality Up 4 IEEE 32 bit CH1 Signal Quality Down 4 IEEE 32 bit CH1 Amp Discriminator Up 4 IEEE 32 bit CH1 Amp Discriminator Down 4 IEEE 32 bit CH1 SNR Up 4 IEEE 32 bit CH1 SNR Down 4 IEEE 32 bit CH2 Signal Quality Up 4 IEEE 32 bit CH2 Signal Quality Down 4 IEEE 32 bit CH2 Amp Discriminator Up 4 IEEE 32 bit CH2 Amp Discriminator Down CH2 SNR Up 4 IEEE 32 bit 4 IEEE 32 bit CH2 SNR Down 4 IEEE 32 bit SMODBUS baud rate MODBUS parity 8MODBUS stop bits MODBUS meter addr 913 299A RESERVED 7 of 9 January 2005 A Notes 1 Clear Totalizers flag from the 8051 to clear either the Channel 1 or Channel 2 totalizers 2 Values in these registers are floating point numbers and require no scaling The number of decimal digits is set in meter programming 3 Require scaling by value in register 13 4 Require scaling by value in register 20 5 AVG Error Code 0 Both Ch1 and Ch2 are in error 1 Ch1 only is in error 2 Ch2 only is in error 3 Both channels are error free 6 MODBUS baud rate 5 2400 6 4800 7
8. ed in the GC868 only the card in slot 5 is activated Setting Up MODBUS To set up MODBUS communications enter the User Program as Communications described in your Programming Manual Then refer to the menu map in Figure 1 on page 9 and complete the following steps Note Any time the following settings are changed the GC868 must be rebooted to load the new settings into the option card Press the key and then the F3 key to select the COMM submenu On a two channel GC868 pressing the gt key and the F3 key accesses the GLOBL menu Then press F4 to ACTIV EAM PIPE l ne select the COMM submenu IMPORTANT The serial port settings of the GCS68 must match those of the MODBUS control system 913 299A 2 of 9 January 2005 A Setting Up MODBUS Communications cont COMM PROGRAM This baud rate applies only to the RS232 serial port Press the gt until the desired RS232 baud rate appears on the option bar and press the appropriate Fx current value appears here function key to select it tn E ET The available RS232 baud rates are 300 600 1200 2400 4800 9600 and 19200 COMM PROGRAM The UART bits setting applies BAUD RATE only to the RS232 serial port current value appears here Press the until the desired RS232 UART bits setting UART bits appears on the option bar and current setting appears here then press the appropriate Fx 8 n0 ETI seven J 7 no function key to select it
9. nt 4 2 16 bit int Signal Strength Upstream 4 2 16 bit int Signal Strength Downstream Temperature 4 2 16 bit int 4 2 16 bit int Pressure 4 2 16 bit int Signal Quality Up Signal Quality Down 4 IEEE 32 bit 4 IEEE 32 bit Amp Discriminator Up 4 IEEE 32 bit Amp Discriminator Down SNR Up 4 IEEE 32 bit 4 IEEE 32 bit SNR Down 4 IEEE 32 bit 6MODBUS baud rate MODBUS parity 8MODBUS stop bits MODBUS meter addr 913 299A RESERVED 5of9 MODBUS Reg DPR Hex Addr Description Clear Ch1 Totalizers Table 3 MODBUS Registers for a 2 Channel GC868 Scaling decimal places January 2005 Size in Bytes 2 16 bit signed Clear Ch2 Totalizers 2 16 bit signed Ch1 Velocity 4 2 16 bit int 2Ch1 Act Volumetric Q DIGITS 4 IEEE 32 bit 2Ch1 Std Volumetric Q DIGITS 4 IEEE 32 bit 3Ch1 Fwd Totals T DIGITS 4 2 16 bit int 3Ch1 Rev Totals T DIGITS 4 2 16 bit int Ch1 Tot Digits 0 2 2Ch1 Mass Flow M DIGITS 4 IEEE 32 bit 4Ch1 Fwd Mass Totals 4Ch1 Rev Mass Totals MT DIGITS MT DIGITS 4 2 16 bit int 4 2 16 bit int Ch1 Mass Tot Digits 2 Ch1 Timer 4 2 16 bit int Ch1 Error Code 2 Ch1 Sound Speed 4 2 16 bit int Ch1 Density 4 2 16 bit int Ch1 Sig Strength Upstream
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