Communicating with Gas Chromatographs
Contents
1. Component Stream and current GC date and time Attempt to read Modbus point 3034 through 3040 7 registers If the GC provides a good response go to step 3 or else go to step 1 Step 3 Get Component Mole s Attempt to read Modbus points 7001 through 7024 24 32 bit IEEE floats in normal OMNI format If itis a good response go to step 4 else go to step 1 Note that the OMNI reads more than the 16 Mole s that are available in the Danalyzer This is done for compatibility with Houston Atlas GC which has more components available but otherwise emulates a Danalyzer Step 4 Get BTU Dry BTU Saturated at Base BTU Wet and Total un normalized Mole NOTE GC Heating Value On Application 27 75 user is allowed to select either the actual BTU 7054 or Dry Superior 7033 in their calculation Currently the default is Dry Superior when actual BTU is set to 0 0 Attempt to read Modbus points 7033 through 7054 22 32 bit IEEE floats If good response go to step 5 or else go to step 1 Point 7054 actual BTU usually is the same as point 7033 dry BTU but can be manipulated within the GC to include an estimated H20 effect The OMNI uses point 7054 as the actual BTU for internal use Point 7038 un normalized Total Mole is compared to 100 If the deviation exceeds a user entered value the GC will be logged as having failed and fixed values will be used for the analysis While the SG and BTU data in the GC is norm2. this analysis pertains to OMNI checks this 3045 Cycle start time minutes When this changes OMNI assumes new analysis 3059 Cal Analysis Flag If 0 indicates that analysis is a calibration run and should be ignored 3046 Contains Alarm Flags See GC Manual MSB 15 checksum failure and Bit 14 analyzer failure ON will fail the GC 3047 Contains Alarm Flags See GC Manual Bits 3 adjust preamp and 2 preamp failure ON will fail the GC 7001 7024 Can contain up to 24 component mole s C6 if present is usually located in 7001 7035 Contains Relative Density SG 7038 Contains Total Un Normalized mole s 7054 Contains Actual BTU Normalized GC Composition GC components should be normalized when received by the flow computer If using AGA5 or GPA2172 heating value no additional normalization is performed Selecting ISO6976 and using Revision 23 27 74 30 and higher will provide normalization C9 Component GC with C9 component should enter this component under the n Nonane using the next number in sequence for the component order from the GC 52 0001 0008 Rev C Page 5 of 7 5 E TB 080000C Communicating with Gas Chromatographs Model 2251 Chromatograph Controller US Versions and ISO Version The main difference between the USA and ISO versions of the Model 2251 is the following US Version Index Description 7033 BTU Dry 7034 BTU Saturated 7035 Specific Gravity 7036 Com
3. Last Updated 13 July 2010 TB 080000C Technical Bulletin Communicating with Gas Chromatographs OMNI FLOW COMPUTERS INC ps 1 e 12620 West Airport Boulevard Suite 100 US Omni Sugar Land Texas 77478 United States of America Phone 281 240 6161 Fax 281 240 6162 www omniflow com 52 0001 0008 Rev C Page 1 of 7 TB 080000C Communicating with Gas Chromatographs NOTE User Manual Reference This Technical Bulletin complements the information contained in the User Manual applicable to Revision 23 74 27 74 Table of Contents E1010 01E rs eons att a cite vase es T EE ah mata garb tentmuetea E T 3 ADStraChinis 6 23 fod Guth NAE et i edo eee et es ee ee es 3 GC to OMNI Flow Computer Communications cece eceeeeeeceeeeeeeeeeeeeeeeeeaeeeeeeeeaaeeeeentaeeeenens 3 Sellal molp i te a EEE EEE EEEE EE E eye loees E ieee eastoietvale aes 4 Step 1 Check GC to see if new analysis is available 0 cc ceeeceseteeeeeeeeeeeeesseeeeeeeeeeeeess 4 Step 2 Get Component Stream and current GC date and time ccccccceeeeesstteeeeeeeeeeeees 4 Step 3 Get Component Mole Sxisvciiesicis ty si cdossuers canntavelon Merisiden duadhianem eel nnna rannen eee 4 Step 4 Get BTU Dry BTU Saturated at Base BTU Wet and Total un normalized Mole 4 Step 5 Determine how to handle C6 and ratio into C6 C7 and C8 according to code 5 Normalized GC Composition sicsac coc scigpaceceusdecccvngqess teeeduqutecentic
4. acnegesiss Bedend ddan aceedaoreduesagieratoadeentuces 5 C9FG mponentnros ne aen a ne a A Sec ta aa aes 5 Model 2251 Chromatograph Controller US Versions and ISO VerSiONn cccccsseeeeereeeeeees 6 52 0001 0008 Rev C Page 2 of 7 5 E TB 080000C Communicating with Gas Chromatographs Scope This Technical Bulletin applies to application firmware revisions 23 744 and 27 74 of OMNI 6000 OMNI 3000 Flow Computers for gas flow metering systems which can apply a Gas Chromatograph The OMNI Flow Computer can communicate via serial on Port 3 with any Gas Chromatograph such as the Danalyzer SIM 2251 ABB NGC8206 or any other GC which can emulate the Danalyzer process When communicating to a Danalyzer or ABB NGC8206 Modbus ASCII or RTU is used Current firmware applications 23 and 27 provide the option to add a second Gas Chromatograph in multi drop mode via serial Port 3 Additional override codes for Gas Chromatograph 2 are listed in OmniCom Users should note that when using overrides codes with Gas Chromatograph 2 it is mandated that Gas Chromatograph 1 and Gas Chromatograph 2 have identical stream configurations Applied Automation GC which uses the AA proprietary HCI A protocol interface can also be used but the user must select the Applied Automation GC in the Analyzer setup menu Abstract The Gas Chromatograph provides a compositional analysis of the gas exported through the Gas Metering Skid It is supplie
5. ally not component data the flow computer still needs a number to be entered for each entry Simply assign the next two sequential numbers after all the other components have been entered 52 0001 0008 Rev C Page 4 of 7 5 E TB 080000C Communicating with Gas Chromatographs Step 5 Determine how to handle C6 and ratio into C6 C7 and C8 according to code Attempt to read register 3001 1 register If a bad response go to step 1 else determine if the contents of 7001 relate to C6 by checking the value of 3001 If 3001 108 or 08 7001 C6 Ratio 47466 3534 17194 If 3001 109 or 09 7001 C6 Ratio 50 50 0 0 If 3001 110 or 10 7001 C6 Ratio 50 25 25 If 3001 111 or 11 7001 C6 Ratio 57143 28572 14285 If 3001 is none of these codes 7001 is considered not to contain C6 and will be allocated as specified in the OMNI Analyzer Setup menu This menu is where the user specifies what components are contained in what fields NOTE Beginning with revisions 23 74 and 27 74 of OMNI firmware you specify the breakdown ratios of the C6 through C10 components in the OMNI configuration therefore the OMNI no longer reads GC register 3001 List of critical data points used by the OMNI Each of these points are embedded within one of the blocks of data described above 3001 Code defining the contents of floating point register 7001 OMNI checks for C6 3034 Specifies what stream
6. d with a representative sample of the gas via a pressure letdown system which reduces the pressure from line conditions to analyzer conditions A typical process Gas Chromatograph is fitted with three 3 columns These are very small bore tubes of differing lengths packed with molecular separation material known as the stationary phase and a series of switching values to divert the flow via various column combinations This equipment is housed in an oven which is temperature controlled A constant flow of carrier gas is routed through the columns and values at a typical flow This is used to flush the columns and transport the sample through the columns Prior to a start up the chromatograph is calibrated using a sample cylinder filled with a gas mixture representative of the range of gas components found in the gas line It is very important that the test gas mix is selected as close as possible to that of the line gas as the instrument response is not linear EG if our line gas has a 68 methane content but our test gas has a 74 methane value significant errors may be introduced This is particularly important for the heavier gas components GC to OMNI Flow Computer Communications Action steps below refer to the OMNI Flow Computer accessing the Danalyzer GC database To be compatible the GC must have data points at all of these addresses Many data points are collected for info only and would not be missed could contain zeroes but some are c
7. pressibility 7037 WOBBE Index 7038 Total Unnormalized Mole 7039 Total GPM 7040 Ratio 1 7041 Ratio 2 7042 Ratio 3 7043 Ratio 4 7044 Ratio 5 ISO Version Index Description 7033 HSUP Dry 7034 HSUP Saturated 7035 Relative Density 7036 Compressibility 7037 WOBBE Index 7038 Total Unnormalized Mole 7039 N A See Note below NOTE GPM is available on US versions of the Models 2251 and 2255 only ISO versions of the controller will contain weight only Additional information can be found on the www Emersonprocess com web site 52 0001 0008 Rev C Page 6 of 7 TB 080000C Communicating with Gas Chromatographs DOCUMENT REVISION HISTORY DOCUMENT INITIAL RELEASE DATE cc ccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 03 May2008 REVISION DATE PURPOSE CHANGE REQUEST A 03 May 2008 Maintained on the Web Initial release B 09 April 2009 DCR 090099 C 13 July 2010 DCR 100120 52 0001 0008 Rev C Page 7 of 7 Omni
8. ritical and must be present a list is provided at the end of this Technical Bulletin The OMNI Flow Computer Rev 23 27 application Serial Port 3 should be set to the following per Danalyzer GC recommendations 52 0001 0008 Rev C Page 3 of 7 5 E TB 080000C Communicating with Gas Chromatographs Serial Port 3 Baud Rate 9600 Stop Bits 1 Data Bits 7 Parity Even Xmit Key Delay 0 Protocol type 5 Danalyzer ASCII CRC enabled Y The GC would be set as follows Port usage SIM_2251 Baud Rate 9600 Data Bits 7 Stop Bits 1 Parity Even Handshake None RTS On 0 RTS Off 0 PRTCL ASCII Comm ID 1 RW RW Wiring examples are as follows assumes GC Com3 is configured for RS 485 or GC COM1 is configured for RS 232 RS 485 2 wire OMNI 6000 TB4 pin 1 to Danalyzer GC J10 Com3 pin 2 OMNI 6000 TB4 pin 4 to Danalyzer GC J10 Com3 pin 5 OMNI 6000 TB4 pin 5 to Danalyzer GC J10 Com3 pin 3 RS 232 OMNI 6000 TB4 pin 1 to Danalyzer GC J5 Com1 pin 3 OMNI 6000 TB4 pin 3 to Danalyzer GC J5 Com1 pin 2 OMNI 6000 TB4 pin 4 to Danalyzer GC J5 Com1 pin 5 Step 1 Check GC to see if new analysis is available Read Modbus point 3041 through 3059 19 registers Check 3045 GC Cycle Start Time Minutes if this has changed go to step 2 otherwise wait for Results Interval Timer to time out adjustable in minute increments but usually set to 1 min and repeat step 1 Step 2 Get
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