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FIELDBUS Segment Calculator V1.5.0 V1.5.0 : October 2004 MTL FIELDBUS Segment Calculator Index 1 Introduction 1.0 Design Principles 1.1 MTL Power Sources 2 Flow chart of Worksheets 2.1 The Main Menu 2.2 The Segment Sheet 2.3 Instrument Data Sheet 2.4 Front Sheet 2.5 Key Notes Sheet 2.6 Excel Screen Settings 3 Basic Design Mode 3.1 Main Menu 3.2 Segment Sheet 3.3 Megablock Selection 3.4 Minimum Segment Voltage 3.5 Cable Resistance 3.6 Length of Segment 3.7 Segment Voltages 3.8 Megablock models available 3.9 System Parameters 3.10 Megablock Internal Voltage drop 3.11 10-Way Megablock 3.12 System Check 3.13 Clear Check 3.14 Clear IS/SG Level 3.15 ‘Clear Screen’ & ‘Partial Clear’ 3.16 Megablocks Allocated 3.17 Instrument Data Sheet 3.18 Printing 3.19 Project Documentation 3.20 Moving between Worksheets 4.0 System Check 4.1 Line voltage 4.2 Segment Current 4.3 Spur Excessive Currents 4.4 Spur Short-Circuit Currents 4.5 Fieldbus Cable Length 4.6 Instrument Count 4.7 Cable Resistance Specification 5 Instrument Data Sheet
Transcript
Page 1: fieldbus calculator_user manual

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MTL FIELDBUS Segment Calculator

Index

1 Introduction 1.0 Design Principles 1.1 MTL Power Sources

2 Flow chart of Worksheets 2.1 The Main Menu 2.2 The Segment Sheet 2.3 Instrument Data Sheet 2.4 Front Sheet 2.5 Key Notes Sheet 2.6 Excel Screen Settings

3 Basic Design Mode 3.1 Main Menu 3.2 Segment Sheet 3.3 Megablock Selection

3.4 Minimum Segment Voltage 3.5 Cable Resistance 3.6 Length of Segment 3.7 Segment Voltages 3.8 Megablock models available 3.9 System Parameters 3.10 Megablock Internal Voltage drop 3.11 10-Way Megablock 3.12 System Check 3.13 Clear Check

3.14 Clear IS/SG Level 3.15 ‘Clear Screen’ & ‘Partial Clear’ 3.16 Megablocks Allocated 3.17 Instrument Data Sheet 3.18 Printing 3.19 Project Documentation 3.20 Moving between Worksheets

4.0 System Check 4.1 Line voltage 4.2 Segment Current 4.3 Spur Excessive Currents 4.4 Spur Short-Circuit Currents 4.5 Fieldbus Cable Length 4.6 Instrument Count 4.7 Cable Resistance Specification 5 Instrument Data Sheet

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5.1 Description of Instrument Data Sheet Facilities 5.1.1 Power Conditioner 5.1 2 MegaBlock Hubs 5.1 3 Trunk surge devices 5.1.4 Additional Segment devices 5.1.5 Instrument Current consumption 5.1.6 Data Transfer to Segment Sheet 5.1.7 Data transfer of Segment Sheet Data to the Instrument Data Sheet. 5.1.8 Typical Engineering Process Data

6.0 Appendix – Error Codes

7.0 Conditions of Use of the Fieldbus Calculator

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1 Introduction 1.0 Design Principles The Calculator is essentially a tool to assess voltages, currents, and various other parameters associated with a user-designed fieldbus segment. It allows for an inventory to be taken of all the components specified within a design, thus ensuring an account is taken of all the required materials. It takes no consideration of the user having made the correct choice of components with regard to hazardous area location, nor the resulting nature of the networks, ie, whether they become Non-Incendive, Non-Arcing, or Intrinsically Safe. Two fundamental approaches are available using the Calculator : • A facility whereby the user may simply make a choice of the power conditioner

being employed, after which the fieldbus segment is constructed using various Megablock devices. Cable parameters are then entered and instruments added to complete the system design, using the ‘System Check’ to ensure the design is a practical application. Warning flags are raised if significant parameters are exceeded. Note that in this mode of program application it is not possible to add surge protection devices, Entity or Zone 0 interfaces.

• The more comprehensive approach is to use the Instrument Data page to create a complete map of the required network. This facilitates, where required, the importing of system data from previously engineered process layouts. A sample spreadsheet of such a file is available for perusal & experimentation and may be downloaded from the web site. This approach allows for the application of surge protection devices, Entity or Zone 0 interfaces to the main segment trunk and to each attached spur. Cable parameters are then entered to complete the system design, using the ‘System Check’ to ensure the design is a practical application.

In conclusion, using either of the above methods, an inventory of the required components may be displayed, and the configured design printed out. The completed design may of course be saved as a standard Excel file, using a unique name that relates to the project under consideration, forming part of the system documentation. At any future time it can be recalled for modification or review.

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1.1 MTL Power Sources The program caters for the range of MTL Power Sources :

Power Source Model9121-IS 9122-IS 9111-NI 9112-NI

FPS (See * ) MTL5995 MTL5053

Note * : There are several versions of the FPS Power Supply : FPS-I Redundant power system Terminator fitted on device carrier FPS-2 Redundant power system No Terminator FPS-DT Dual power system Terminator fitted on device carrier FPS-D Dual power system No Terminator F600A Redundant power system for use with Yokogawa ALF111 card F650A Redundant power system for use with Honeywell Experion PKS FIM As the facilities offered by the Calculator are enhanced, the latest versions will be posted on the MTL web site, and will be freely downloadable. 2 Flow chart of Worksheets Fig 2.1 illustrates the interconnection of the design pages of the program. Buttons are available on each sheet to move efficiently between the various pages described. Fig 2.1

Main Menu

Key Notes Sheet

Front Sheet

Instrument Data Sheet

Segment Sheet

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2.1 The Main Menu lists the power conditioners that are available, as listed in Section_1.1. 2.2 The Segment Sheet is where the fieldbus segment layout is created, where all components are graphically laid down, and where the System Check is carried out. An inventory of segment components may also be listed. 2.3 Instrument Data Sheet is where the more advanced mode of segment preparation is carried out. It is here that data may be imported from previously engineered data. Components such as surge protection devices, interfaces to allow for the connection of Entity certified instruments, and interfaces for connecting instruments located in Zone 0, may be added to the segment layout. 2.4 Front Sheet For documentation purposes the project management details may be contained here, the headings being user-editable where required. This data forms the front sheet of a hard-copy print out. 2.5 Key Notes Sheet Information is given here regarding significant features that might affect how the program is used, eg, the ability to select the User Minimum Network Voltage. This sheet is for information advice only. 2.6 Excel Screen Settings As soon as the program is run many of the familiar screen settings used with Excel are removed to assist in providing a clear display. These settings may persist once the program is terminated, and other Excel programs loaded. The familiar settings may be restored by selection of the menu options as under :

a) Select ‘View’, & check ‘Formula Bar’ to restore the Excel Formula Bar. b) Select ‘View’, & check ‘Status Bar’ to restore the Excel Status Bar c) Select ‘View’, ‘Toolbars’ & check ‘Formatting’ to restore the Excel

Formatting menu view d) Select ‘View’, ‘Toolbars’ & check ‘Drawing’ to restore the Excel Drawing

menu view e) Select ‘Tools’, ‘Options’, ‘View’; check ‘Row & Column Headers’; check

‘Sheet Tabs’

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3 Basic Design Mode This section describes the basic mode of design whereby the user lays down the network without reference to engineering data in electronic format. 3.1 Main Menu Starting the program at the Main Menu, select the type of power source being deployed, after which the user is automatically taken to the Segment Sheet.

Power Source Model Nominal voltage

available

Nominal current

available

Ex – protection

9121-IS 12.4 120 mA IS (ib) 9122-IS 13.1 265 IS (ib) 9111-NI 12.4 180 NI (Zone 2) 9112-NI 13.1 320 NI (Zone 2)

FPS-I 25.0 350 NA (Zone 2) MTL5995 19.0 350 NA (Zone 2) MTL5053 18.05 80 IS (ia)

IS : Intrinsically Safe source NI (Zone 2) : Non-Incendive source : for application only in safe area or Zone 2 NA (Zone 2) : Non-Arcing source : for application only in safe area or Zone 2 If at any stage of using the Segment Sheet the power source definition appears blank, then return to the Main Menu to make an appropriate selection. If a system design is partially completed, but recourse is made to the Main Menu to select an alternative power source device it is essential to subsequently call the ‘System Check’ facility to ensure that the new configuration still indicates a satisfactory layout. 3.2 Segment Sheet On entry to the Segment Sheet, the type of Megablock about to be placed will default automatically to :

• IS Megablocks when any IS power conditioner has been selected. • Non-IS Megablocks with Spurguard when any Non-IS power conditioner has

been selected. The user may over-ride this choice by selecting the ‘SpurGuard’ or ‘IS’ buttons accordingly, but a warning will be given regarding the action taken.

• Choosing a Non-IS Megablock with an IS power conditioner might create an unsafe, uncertified network.

• Choosing a Non-IS Megablock without Spurguard might create an unreliable network where a single point of (spur) failure could jeopardise the operation of the whole network.

Such changes are not recommended by MTL in view of the possible conflict. Note that once a Megablock is laid down on the segment, the type can only be changed by complete removal of that node and re-applied in its modified form.

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3.3 Megablock Selection Select the sequence of Megablock devices being deployed, in the order in which they will appear along the fieldbus segment. The screen display will show the selection accordingly. The program allows for a maximum of four devices to be connected in cascade, which is felt will satisfy the majority of fieldbus applications. It may be useful to include the physical location of each Megablock on the process plant. This designation could, for instance, be entered in the cell directly above the position of the Megablock, remembering that all entries on the spreadsheet will be saved with the overall file, or printed out as part of the system documentation (see Fig 3.1)

Fig 3.1

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3.4 Minimum Segment Voltage A default minimum segment voltage of 9.0 volts is automatically inserted, this being the specified operating minimum for all fieldbus instruments. This value may, however, be overwritten at any time to allow for a further margin of operation in any calculations. This is achieved by entering the required value in the appropriate cell on the ‘Segment’ worksheet. 3.5 Cable Resistance Referring to the Foundation Fieldbus document ag-181 four different cable specifications are given for fieldbus operation :

Cable type Resistance per loop kilometre

Screened cable

Type ‘A’ 44 Ω Individually screened / twisted pairs Type ‘B’ 112 Ω Overall screen / twisted pairs Type ‘C’ 264 Ω Twisted pairs / No screen Type ‘D’ 40 Ω Multi-core / No screen

Selection of the cable type (and its resistivity) is made on the Segment Sheet. Selecting the ‘Apply’ button will globally insert the selected value in all trunk & segment spurs. Variations may subsequently be made to individual trunks and/or spurs, where a non-compliant cable is being employed, by simply entering an appropriate value in a given cell. Where resistance values are left blank any calculation will assume that an instrument is located adjacent to the Megablock, and the voltage present calculated accordingly. Note : The use of non-screened cable in IS systems located in a hazardous area is not permitted according to the IEC60079-14 Installation Standard. This might preclude the use of Types ‘C’ & ‘D’ above, or similar non-screened cables. 3.6 Length of Segment Enter the length of each part of the segment/spur, and enter the current drawn by each instrument. The system assumes that a single instrument is attached per spur when reporting the number of instruments deployed on the segment. 3.7 Segment Voltages Voltages along the segment are displayed instantly as the parameters are entered.

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3.8 Megablock models available :

Model Spurs SpurGuard Applications FCS-MB2 2 GP/NA/NI/IS FCS-MB2-SG 2 Yes GP/NA Trunk/NI spurs FCS-MB4 4 GP/NA/NI/IS FCS-MB4-SG 4 Yes GP/NA Trunk/NI spurs FCS-MB8 8 GP/NA/NI/IS FCS-MB8-SG 8 Yes GP/NA Trunk/NI spurs FCS-MB10-T 10 GP/NA/NI/IS FCS-MB10-SG-T 10 Yes GP/NA Trunk/NI spurs F241 2 S/C IS ia F245 4 S/C IS ia F251 8 S/C IS ia F259 10 S/C IS ia

GP : General Purpose (Safe Areas) IS : Intrinsically Safe source S/C : Short Circuit protected spurs NI (Zone 2) : Non-Incendive source : for application only in safe area or Zone 2 NA (Zone 2) : Non-Arcing source : for application only in safe area or Zone 2 3.9 System Parameters inserted into the selected layout include the following : Overall segment

Minimum acceptable voltage (default = 9.0 volts)

Main Trunk Cable Resistance Ω/loop km

Length of each segment

Spurs Cable Resistance Ω/loop km

Length of each segment

Current drawn

Values reported on-screen with immediate effect : Main Trunk

Voltage at Megablock entry point

Voltage at Megablock exit point

Spurs Voltage at instrument point The display of the above parameters are illustrated below.

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3.10 Megablock Internal Voltage drop Voltage drops occurring, if any, by virtue of a current drawn through a Megablock, are automatically incorporated in the calculations appropriate to the selected hub device. Equally, the small current consumed by each Megablock is automatically included in the calculations. 3.11 10-Way Megablock All 10-way Megablocks contain an integral network terminator. Hence, any attempt to add subsequent devices further down the segment is prevented, with a suitable warning being given. It would be bad fieldbus practice to add further cable & Megablock hub devices after the segment had been terminated. 3.12 System Check Select “System Check” to see all the significant parameters displayed on-screen. See Section 4.0 for a full description. 3.13 Clear Check Having called a ‘System Check’ (above) against the design, causing an appropriate display on the ‘Segment’ worksheet, this display, and any warning messages, may be cleared by selecting the ‘Clear Check’ option. 3.14 Clear IS/SG Level Select this option to clear an otherwise short-circuited spur value of current. See Section 4.4 for a full description. 3.15 ‘Clear Screen’ & ‘Partial Clear’ By selecting ‘Clear Screen’ all the current segment data is deleted, ready to re-commence a new design. If, however, only a portion of a design is to be replaced, the ‘1’, ‘2’, ‘3’, ‘4’ buttons allow for just those hubs to be removed. Subsequently, any further Megablock device selected will be placed in the vacant slot nearest to the power conditioner, in chronological order. Note that any 10-way device must be deployed at the extremity of the network, since they contain a fieldbus terminator. It is not technically practical to cascade further devices after a 10-way device is selected (see 3.10 above). Using the ‘Partial Clear’ function and attempting to insert a 10-way block that precedes other existing blocks is prevented. 3.16 Megablocks Allocated As Megablocks are deployed the device currently assigned to each slot is illustrated on-screen. 3.17 Instrument Data Sheet In many instances Process Loop information is available at an early stage of a project design in spreadsheet format (Excel or Access). If available, this may be imported into the Fieldbus Calculator, facilitating a very efficient compilation of system design. More detailed usage of this mode of design is given later in this document (Section 5).

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3.18 Printing Selecting the ‘Print’ option produces a hard-copy to the default printer currently attached to the PC, the exact content being WYSIWYG. This allows text to be added by users, entering any data relevant to the project on the spreadsheet, and in whichever cell is appropriate, with subsequent hard-copy being available. An example of this might be to enter the location ID of each Megablock directly above the block item, as seen in Fig 3.1. 3.19 Project Documentation Projects may be saved for documentation purposes, or for later amendment, by simply saving the Excel program in its entirety under some user-specific name. Further projects may then be commenced using the base program. 3.20 Moving between Worksheets Switching between various worksheets does not cause loss of the current ‘Segment’ worksheet display & its data. Note, however, that selecting an alternative power source device in this way could result in erroneous data being displayed, since the source voltage & current values may differ from those used in an earlier calculation. This situation can be avoided by simply re-selecting the ‘System Check’ once the power conditioner has been changed. 4.0 System Check Selecting the ‘System Check’ option will report on numerous parameters associated with the completed fieldbus segment. 4.1 Line voltage Depending on the line resistance values & current consumption along each leg of the segment, including spurs, the resulting voltage at each instrument point is reviewed. These levels are compared against the minimum acceptable voltage (9.0 volts by default) set by the user. Any point appearing below this minimum will cause an alarm display. Since this condition could exist at any spur ending, the point/s at which it is occurring is displayed against a red background for ease of identification. Note : Unlike all other power sources featured in this manual, the MTL5053 device has internal source resistance. When specifying an MTL5053 it is essential that the ‘System Check’ option is called, to ensure that this internal resistance is included in the resulting segment calculation. Only by calling ‘System Check’ can the segment current be totalised and the effect of this with the source impedance be calculated. 4.2 Segment Current The accumulation of the current consumption entered for each spur, together with the small amount consumed by the Megablocks, is deduced, and reported in this check. Note that both the Design Current & Current Limit of the chosen power source is displayed, the latter being 20 mA greater than the Design Current.. The Current Limit represents the absolute maximum that can be drawn from a power source, as opposed to the published Design Current for the device. This current margin might allow for a switch-on surge, etc, representing an abnormal operating situation, for in a network operating near its current capacity limit.

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The MTL5053 is unique in not having this margin of difference. An alarm condition, highlighted in red, is given if a figure exceeds the current capacity of the source. 4.3 Spur Excessive Currents Megablocks offering SpurGuard or Intrinsically Safe spur connections have, under normal operation, a maximum available current. This is according to Table 4.1, with values of 58 & 40 mA respectively. Designs demanding a current in excess of these values must be avoided as being above the capacity that can be sourced. Table 4.1 Megablock Technology Maximum current

capacity FCS-MB2-SG SpurGuard 58 mA FCS-MB4-SG SpurGuard 58 FCS-MB8-SG SpurGuard 58 FCS-MB10-SG-T SpurGuard 58 F241 IS 40 F245 IS 40 F251 IS 40 F259 IS 40 4.4 Spur Short-Circuit Currents Megablocks offering SpurGuard or Intrinsically Safe spur connections exhibit a current drain increase to a maximum value if that particular spur is inadvertently short-circuited during operation. This is to a value of 60 & 42 mA, for a SpurGuard or IS device, respectively. The potential effect of this on the total source current drawn will be displayed, highlighted with a red background, as the ‘System Check’ function is selected. The increment introduced will be the difference between the normal current drawn on the spur in question and the value of 60 or 42 mA. The spur furthest down the segment, and also showing the lowest current consumption at that juncture, will automatically be replaced by the fault current. This new value will then feature in the subsequent segment calculations and appear under the ‘Current Limit’ column. The basis for this automatic choice is that the furthest hub, and then the lowest current drawn from that hub, will have the greatest effect on instrument terminal voltages along the segment. To restore the fault value to the user-inserted value, select the ‘Clear IS/SG Level’ button. This must be done prior to further entries being made, eg, more Megablocks added, since a different spur may become the short-circuit focus of interest. Clearly, if a spur offering no short-circuit limit in current is being used it will cause the voltage to collapse, and hence disable the operation of the whole segment, ie, when using those devices listed in Table 4.2. No warning of this possible phenomenon is given when using the Calculator.

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Table 4.2 Megablock Technology FCS-MB2 No bus protection FCS-MB4 No bus protection FCS-MB8 No bus protection FCS-MB10-T No bus protection 4.5 Fieldbus Cable Length When deducing the total length of a fieldbus segment, the Calculator assesses compliance against several specified limits, as contained in Tables 4.3 & 4.4. Table 4.3 Applying Standard Hazard Max. Segment Length including

spurs Foundation Fieldbus FF-816

Safe Area & all hazards

1900 metres (see table below for spur limits)

FISCO or FNICO IIC Gases 1000 metres FISCO or FNICO IIB Gases 1900 metres Cable types Max. Segment Length including

spurs Type ‘A’ 1900 metres Type ‘B’ 1200 metres Type ‘C’ 400 metres Type ‘D’ 200 metres Table 4.4 Fieldbus : Maximum loading recommendations

Total Instrument population

1 device per spur

2 devices per spur

3 devices per spur

4 devices per spur

1-12 120 metres 90 m 60 m 30 m 13-14 90 m 60 m 30 m 0 15-18 60 m 30 m 0 0 19-24 30 m 0 0 0 25-32 0 0 0 0

Any excess outside these limits is reported. In certain design exercises, the application may not require compliance, eg, a Foundation Fieldbus (Entity) project does not have to comply with the 1000 metre limit in a IIC gas, or restrict any spur length to a maximum of 60 metres, as would be the case for a FISCO design. The user should use discretion and ignore irrelevant data. 4.6 Instrument Count The total number of instruments, or more accurately the number of spurs drawing an active current, are deduced. The specified maximum is 32 on a single fieldbus segment, but this is unlikely to be exceeded in practice. Since the utility has no method for the user to assign multiple instruments to a single spur, it is assumed that all active spurs are supporting a single instrument.

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4.7 Cable Resistance Specification Whilst it is important to employ cable to the highest possible specification, resulting in optimum operation, FISCO & FNICO do require cables to be employed having specific parameters. The utility will check that the resistance values inserted throughout the application comply with the requirement for FISCO & FNICO as being between 15 Ω and 150 Ω. Any variation from this produces a warning. Again, the application being designed may not require compliance, eg, a Foundation Fieldbus (Entity) project does not have to comply with this requirement. The user should use discretion and ignore irrelevant data. 5.0 Instrument Data Sheet An illustration of the upper portion of the Instrument Sheet display is shown in Fig 5.1 overleaf. 5.1 Description of Instrument Data Sheet Facilities 5.1.1 Power Conditioner The selected device is shown in the top left hand corner of the sheet. If this is blank then return to the Main Menu to select the required device. 5.1.2 MegaBlock Hubs Up to four Megablock hubs are available, featured to the left of the sheet, this number being assumed to represent the maximum size of envisaged network. 5.1.3 Trunk surge devices Each section of trunk has the facility to define surge protection devices, appearing down the left hand section of the screen. Defining surge protection on a particular trunk section involves the provision of an FP32 device at each end of the section, this being taken into account when listing inventory. 5.1.4 Additional Segment devices Provision is given to add surge protection, an Entity interface, or a Zone 0 interface to each spur. To the right of each block of spur devices is a pointer (red spot) which can be manoeuvred to point at the required spur by operating the adjacent scroll bar. Then selecting the appropriate function button, ie, Surge, Entity, or Zone 0, will add/delete that function to the spur. It is not recommended that both an Entity interface and a Zone 0 interface are used on a single spur. Technically, this will work, and is certifiably safe, but the voltage drop of such a combination is likely to be excessive to the point where the resulting instrument voltage will be below the minimum operating level of 9.0 volts. For this reason the application of both devices to a single spur is prevented. 5.1.5 Instrument Current consumption A further facility on the Instrument Data Sheet is a library of instrument manufacturers data. Select the radio button, at the bottom-right of the screen,

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appropriate to the manufacturer in question; next use the adjacent scroll-bar to move to the specific instrument of interest. The information listed displays : Manufacturer; Device Functionality; Device Model Number; Design Current. Once instrument model types are entered in the Megablock fields, it is possible to automatically insert the current consumption values from this internal database. This is actioned by selecting the ‘Auto-insert Current Drawn’ button. If a particular instrument is not available in the database the ‘Instrument Current’ value field will be left blank. The database of instruments may be reviewed by use of the scroll-bar on the far-right of the screen. If the instrument required appears as a near-match or an alternative instrument identified, the instrument data may be transferred by moving the pointer (red spot) to the spur required, using the scroll-bar, and selecting the appropriate ‘Transfer Instrument Data to Block ‘n’ button. The instrument data and its current consumption will appear in the Megablock window. 5.1.6 Data Transfer to Segment Sheet Once the block information is completed it may then be transferred directly to the Segment Sheet. Select the ‘Write Megablock n’ button to transfer the complete data, including the additional surge, Entity, and Zone 0 interfaces. This will create the size of Megablock on the Segment Sheet, over-writing any previous data on that page. Note : On a blank Segment Sheet, Megablock data must be transferred in the order in which they are required to appear on the Segment Sheet, eg, selecting Block 2 followed by Block 1 to a blank Segment will result in Block 2 being laid down preceding Block 1. 5.1.7 Data transfer of Segment Sheet Data to the Instrument Data Sheet. Exactly the opposite procedure to that described in 5.1.6 is available whereby the Segment Sheet Data may be transferred to the Instrument Data Sheet to enable modifications to be carried out. Note that the only means of adding/modifying Surge devices, Entity, and Zone 0 interfaces is using the Instrument Data Sheet. 5.1.8 Typical Engineering Process Data A typical spreadsheet containing engineering information is included on the web site to illustrate an example of how data may be transferred electronically, thus avoiding human typing errors, and reducing preparation time. In the example given, headings include : • Instrument No. • Plant Location • Instrument Manufacturer • Instrument Type • Instrument Model • Instrument Current • Process Loop Name The spreadsheet example shows several columns of engineering data that might have been pre-prepared for a given project. It defines the size of each Megablock that

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might be required, by reference to the number of instruments required at specific locations. Of the data shown, the last three columns are relevant to the Fieldbus Calculator, viz, Instrument Model, Instrument Current, & Process Loop Name. Using Windows ‘Copy’ & ‘Paste’ the three columns of data described, of the size of the Megablock required, may be quickly transferred into the required cells in the Instrument Data Sheet. The values of current consumption may be quickly applied using the ‘Auto-Insert Current Drawn’ feature (see Section 5.1.5). The data is now ready to create a segment design as described in 5.1.6. The foot of the Instrument Data Sheet contains the table published by Foundation Fieldbus equating the recommended total number of field devices appearing on a fieldbus segment against the number of devices that should be connected per spur of that segment.

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Fig 5.1

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6.0 Appendix – Error Codes When applying additional devices to the Megablock definition on the Instrument Data Sheet certain Error Codes may be brought up adjacent to the selection being made. An interpretation of these errors is given below :

Error type Possible cause

Error A Trying to deploy both Entity & Zone 0 interfaces Error B Zone 0 Interface NOT allowed, eg, with Non-IS power conditioners Error C Entity Interface NOT allowed, eg, with a power conditioner with a

high operating voltage In general, an IS power conditioner is required to use either of the Entity or Zone 0 interfaces, due to excessively high voltages specified by all the other power sources. 7.0 Conditions of Use of the Spreadsheet Express limitation of liability, warranty, indemnification and representation. To the maximum extent permitted by applicable law, MTL Instruments Ltd and its suppliers make no warranties, indemnification, representations, terms or conditions of any kind, express, implied or statutory, about the Fieldbus Calculation Program, the services or suitability, workability, legality or accuracy of the program and its information, or products and services described or contained in the program, and expressly disclaim all implied warranties, terms or conditions of satisfactory quality, merchantability, fitness for a particular purpose, title or non-infringement. In no event will MTL Instruments Ltd be or feel liable with regard to the Fieldbus Calculator Program and its usage to any other party for any consequential, indirect, exemplary, punitive, or special damages that are directly or indirectly related to the Fieldbus Calculation Program, regardless of whether such damages are caused by the ordinary negligence of MTL Instruments Ltd. MTL Instruments Ltd. Power Court Luton Bedfordshire LU1 3JJ UK e-mail [email protected] Tel: +44 (0)1582 723633


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