Chapter F2-04RTD. 4-Channel RTD Input. In This Chapter...

Transcription

1 hapter F-RT -hannel RT Input In This hapter... Module Specifications Setting the Module Jumpers onnecting the Field Wiring Module Operation Writing the ontrol Program

2 hapter : F-RT -hannel RT Input Module Specifications The F-RT -hannel Resistive Temperature etector Input Module provides the following features and benefits: Provides four RT input channels with. F temperature resolution. utomatically converts type Ptq, jptq, Ptq, uq, uq signals into direct temperature readings. No extra scaling or complex conversion is required. Temperature data can be expressed in F or, and as magnitude plus sign or s complement. Precision lead wire resistance compensation by dual matched current sources and ratiometric measurements. The temperature calculation and linearization are based on data provided by the National Institute of Standards and Technology (NIST). iagnostic features include detection of short circuits and input power disconnection. IN F-RT RT H INPUT H+ H H H+ H+ OM H OM H+ H OM H+ H OM H+ H F-RT H+ H H+ F-RT F-RT RT RT TEMP TEMP Module alibration The module automatically re-calibrates every five seconds to remove any offset and gain errors. The F-RT module requires no user calibration. However, if your process requires calibration, it is possible to correct the RT tolerance using ladder logic. constant can be added or subtracted to the actual reading for that particular RT. RT Input onfiguration Requirements The F-RT module requires discrete input points from the PU. The module can be installed in any slot of a L system, including remote bases. The limiting factors on the number of analog modules used are: For local and local expansion systems, the available power budget and number of discrete I/O points. For remote I/O systems, the available power budget and number of remote I/O points. heck the user manual for the particular PU model being used for more information regarding the available power budget and number of local, local expansion or remote I/O points. NOTE: L PUs with firmware release version. or later, L PUs with firmware release. or later, L PUs with firmware release version. or later are required for proper operation. IN INPUT - L nalog Manual, th Edition Rev.

3 hapter : F-RT -hannel RT Input Input Specifications The following table provides the specifications for the F-RT Input Module. Review these specifications to make sure the module meets your application requirements. Input Specifications Number of hannels, differential inputs Pt -.. (- F F) PT -.. (- F F) Input Ranges jpt -.. (- F F) uq -.. (- F F) uq -.. (- F F) Resolution ±., ±. F (±.) bsolute Maximum Ratings Fault Protected Inputs to ±V onverter Type harge alancing, bit Sampling Rate ms per channel Linearity Error (End to End) ±. maximum, ±. typical PL Update Rate channels/scan max. / / PU channel/scan max. PU Temperature rift ppm / maximum Maximum Inaccuracy ± RT Excitation urrent µ ommon Mode Range V Notch Filter > d /Hz f -d =.Hz () input points igital Input Points Required binary data bits, sign bit, channel I bits fault bits Power udget Requirements V (supplied by base) Operating Temperature ( F) Storage Temperature - (- F) Relative Humidity % (non-condensing) Environmental ir No corrosive gases permitted Vibration MIL ST. Shock MIL ST. Noise Immunity NEM IS- L nalog Manual, th Edition Rev. -

4 hapter : F-RT -hannel RT Input Special Placement Requirements (L and Remote I/O ases) It is important to examine the configuration if a L PU is being used. s can be seen in the section on Writing the ontrol Program, V-memory locations are used to manage the analog data. If the module is placed so that the input points do not start on a V-memory boundary, the instructions will not be able to access the data. This also applies when placing this module in a remote base using a -RSS in the PU slot. Refer to the diagrams below. orrect! To use the V-memory references required for a L PU, the first input address assigned to the module must be one of the following locations. The table also shows the V-memory addresses that correspond to these locations. pt Output Y Y ata is correctly entered so input points start on a V-memory boundary address from the table below. MS Incorrect V ata is split over three locations, so instructions cannot access data from a L. MS V LS MS MS V V V V V V V V V pt Output Y Y pt Input F-RT Slot Slot Slot Slot Slot LS V pt Output Y Y pt Input - pt Input V V V V V LS pt Output LS Y Y pt Input MS pt Input F-RT Slot Slot Slot Slot Slot V pt Input - LS - L nalog Manual, th Edition Rev.

5 hapter : F-RT -hannel RT Input Setting the Module Jumpers Jumper Locations Locate the bank of seven jumpers (J) on the P board. Notice that the description of each jumper is on the P board. The following options can be selected by installing or removing the jumpers: Number of channels:. The input type: q or q copper, jptq, Ptq or Ptq RTs Temperature conversion: s complement or magnitude plus sign format in Fahrenheit or elsius. To prevent losing a jumper when it is removed, store it near its original location by sliding one of its sockets over a single pin. Selecting the Number of hannels The two jumpers labeled H+ and H+ are used to select the number of channels that will be used. The factory default setting is four-channel operation (both jumpers installed). ny unused channels are not processed. For example, if you select channels, channel will be inactive. The table shows how to arrange the jumpers to select the number of channels. = jumper installed, empty = space = jumper removed Number of Jumper hannels H+ H+ H+ H+ RT- RT- RT- Units- Units- Jumper escriptions Setting Input Type The jumpers labeled RT-, RT-, and RT- are used to select the type of RT. The module can be used with many types of RTs. ll channels of the module must be the same RT type. The default setting from the factory is Ptq (RT- comes with the jumper removed). This selects the IN European type RT. European curve type RTs are calibrated to IN, S, or IE specifications which is (. q/q/ ( =.q). The jptq type is used for the merican curve (. q/q/ ), platinum q RTs. The q and q RT settings are used with copper RTs. J L nalog Manual, th Edition Rev. -

6 hapter : F-RT -hannel RT Input The table shows how to arrange the jumpers to set the input type. = jumper installed, empty space = jumper removed. RT Inputs Jumper Pins RT- RT- RT- u q u q jpt q Pt q Pt q Selecting the onversion Units Use the last two jumpers, Units- and Unit-, to set the conversion unit. The options are magnitude + sign or s complement in Fahrenheit or elsius. The module comes from the factory with both jumpers installed for magnitude + sign conversion in Fahrenheit. ll RT types are converted into a direct temperature reading in either Fahrenheit or elsius. The data contains one implied decimal place. For example, a value in V-memory of would be. or F. Negative temperatures can be represented in either s complement or magnitude plus sign form. If the temperature is negative, the most significant bit in the V-memory location is set (). The s complement data format may be required to correctly display bipolar data on some operator interfaces. This data format could also be used to simplify averaging a bipolar signal. To view this data format in irectsoft, select Signed ecimal. The table shows how to arrange the jumpers. = jumper installed, empty space = jumper removed. Number Temperature onversion Units of Magnitude + Sign s ompliment hannels F F Units- Units- - L nalog Manual, th Edition Rev.

7 hapter : F-RT -hannel RT Input onnecting the Field Wiring Wiring Guidelines Your company may have guidelines for wiring and cable installation. If so, check the guidelines before beginning the installation. Here are some general things to consider: Use the shortest wiring route whenever possible. Use shielded wiring and ground the shield at the transmitter source. o not ground the shield at both the module and the source. o not run the signal wiring next to large motors, high current switches, or transformers. This may cause noise problems. Route the wiring through an approved cable housing to minimize the risk of accidental damage. heck local and national codes to choose the correct method for your application. To remove the terminal block, disconnect power to the PL and the field devices. Pull the terminal block firmly until the connector separates from the module. You can remove the RT module from the PL by folding out the retaining tabs at the top and bottom of the module. s the retaining tabs pivot upward and outward, the module s connector is lifted out of the PL socket. Once the connector is free, you can lift the module out of its slot. Use the following diagram to connect the field wiring. If necessary, the F RT terminal block can be removed to make removal of the module possible without disturbing field wiring. RT - Resistance Temperature etector Use shielded RTs whenever possible to minimize noise on the input signal. Ground the shield wire at one end only, preferably at the RT source. Lead onfiguration for RT Sensors The suggested three-lead configuration shown below provides one lead to the H+ terminal, one lead to the H terminal, and one lead to the common terminal. ompensation circuitry nulls out the lead length for accurate temperature measurements. Some sensors have four leads. When making connections, do not connect the second lead to the H+ input; leave that lead unconnected. o not use configurations that lack Wiring onnections For Typical RT Sensor the use of the same color lead to both the H and OM terminals. There Red To H Red is no compensation and temperature To OM readings will be inaccurate. This module has low RT excitation current, the worse case dissipation with q RTs connected is only. mw. Sensor White To H+ White (if applicable) No onnection (if sensor has leads, only connect one lead to H+) L nalog Manual, th Edition Rev. -

8 hapter : F-RT -hannel RT Input mbient Variations in Temperature The F-RT module has been designed to operate within the ambient temperature range of. Precision analog measurement with no long term temperature drift is assured by a chopper stabilized programmable gain amplifier, ratiometric referencing, and automatic offset and gain calibration. Wiring iagram The F-RT has a terminal block which simplifies wiring and can be removed to make removal of the module possible without disturbing field wiring. Note Note x V h - h+ h - h + h h + h h + nalog Multiplexer μ urrent Source Ref. dj. μ urrent Source NOTE : The three wires connecting an RT to the module must be the same type and length. o not use the shield or drain wire for the third connection. NOTE : If an RT sensor has four wires, the plus (+) sense wire should be left unconnected as shown. + - / IN F-RT RT INPUT H H+ H H+ OM OM H H+ H H+ F-RT RT TEMP - L nalog Manual, th Edition Rev.

9 hapter : F-RT -hannel RT Input Module Operation efore beginning to write the control program, it is important to take a few minutes to understand how the module processes the analog signals. hannel Scanning Sequence for a L PU (Multiplexing) The F-RT module can supply different amounts of data per scan, depending on the type of PU being used. The L can obtain one channel of data per PU scan. Since there are four channels, it can take up to four scans to get data for all channels. Once all channels have been scanned the process starts over with channel. Unused channels are not processed, so if only two channels are selected, each channel will be updated every other scan. The multiplexing method can also be used for the L/-/ PUs. Scan Read Inputs Execute pplication Program Read the data Store data Write tooutputs Scan N Scan N+ Scan N+ Scan N+ Scan N+ System With L PU hannel hannel hannel hannel hannel L nalog Manual, th Edition Rev. -

10 hapter : F-RT -hannel RT Input hannel Scanning Sequence for L, L- and L PUs (Pointer Method) If a L, a L- or a L PU is being used, all four channels of input data can be captured in one scan. This is because the L/-/ PUs support special V-memory locations that are used to manage the data transfer. This is discussed in more detail in the next section on Writing the ontrol Program. Scan Read Inputs Execute pplication Program Read the data Store data Write tooutputs Scan N Scan N+ Scan N+ Scan N+ Scan N+ System With L/ - / PU h,,, h,,, h,,, h,,, h,,, nalog Module Updates Even though the channel updates to the PU are synchronous with the PU scan, the module asynchronously monitors the analog transmitter signal and converts the signal to a -bit binary representation. This enables the module to continuously provide accurate measurements without slowing down the discrete control logic in the RLL program. The time required to sense the temperature and copy the value to V-memory is ms minimum to ms plus scan time maximum (number of channels x ms + scan time). - L nalog Manual, th Edition Rev.

11 hapter : F-RT -hannel RT Input Writing the ontrol Program Reading Values Pointer Method and Multiplexing There are two methods of reading values: Pointer method Multiplexing The multiplexing method must be used with a L PU. The multiplexing method must also be used with remote I/O modules (the pointer method will not work). Either method can be used with the L, L- and L PUs, but for ease of programming it is highly recommended to use the pointer method. Pointer Method for the L/-/ PUs The PU has special V-memory locations assigned to each base slot that greatly simplifies the programming requirements. These V-memory locations: Specify the number of channels to scan. Specify the storage locations. The example program shows how to setup these locations. Place this rung anywhere in the ladder program, or in the initial stage if stage programming instructions are used. This is all that is required to read the data into V-memory locations. Once the data is in V-memory, math instructions can be used on the data, compare the data against preset values, etc. V is used in the example, but any user V-memory location can be used. The module is installed in slot for the examples. Use the V-memory locations shown in the application. The pointer method automatically converts values to. NOTE: L PUs with firmware release version. or later and L PUs with firmware release version. or later support this method. Use the L multiplexing example if the firmware revision is earlier. SP L -or- L K K V L O V Loads a constant that specifies the number of channels to scan and the data format. The upper byte, most significant nibble (MSN) selects the data format (=, =inary), the LSN selects the number of channels (,,, or ). The binary format is used for displaying data on some operator interfaces. The L/ PUs do not support binary math functions, whereas the L does. Special V-memory location assigned to slot that contains the number ofchannels to scan. This loads an octal value for the first V-memory location that will be used to store the incoming data. For example, the O entered here would designate the following addresses: h - V, V, h - V, V, h - V, V, h - V, V. The octal address (O) isstored here. V isassigned toslot and acts as a pointer, which means the PU will use the octal value in this location to determine exactly where tostore the incoming data. L nalog Manual, th Edition Rev. -

12 hapter : F-RT -hannel RT Input The following tables show the special V-memory locations used by the L, L- and L for the PU base and local expansion base I/O slots. Slot (zero) is the module next to the PU or -M module. Slot is the module two places from the PU or -M, and so on. Remember, the PU only examines the pointer values at these locations after a mode transition. lso, if the L (multiplexing) method is used, verify that these addresses in the PU are (zero). The Table below applies to the L, L- and L PU base. PU ase: nalog Input Module Slot-ependent V-memory Locations Slot No. of hannels V V V V V V V V Storage Pointer V V V V V V V V The Table below applies to the L- or the L PU base. Expansion ase -M #: nalog Input Module Slot-ependent V-memory Locations Slot No. of hannels V V V V V V V V Storage Pointer V V V V V V V V The Table below applies to the L- or the L PU base. Expansion ase -M #: nalog Input Module Slot-ependent V-memory Locations Slot No. of hannels V V V V V V V V V V V V V V V V The Table below applies to the L PU base. Expansion ase -M #: nalog Input Module Slot-ependent V-memory Locations Slot No. of hannels V V V V V V V V Storage Pointer V V V V V V V V The Table below applies to the L PU base. Expansion ase -M #: nalog Input Module Slot-ependent V-memory Locations Slot No. of hannels V V V V V V V V Storage Pointer V V V V V V V V - L nalog Manual, th Edition Rev.

13 hapter : F-RT -hannel RT Input Negative Temperature Readings with Magnitude Plus Sign for the L, L- and L PUs (Pointer Method) With bipolar ranges, some additional logic will be needed to determine whether the value being returned represents a positive voltage or a negative voltage. For example, the direction for a motor might need to be known. There is a solution for this: If bipolar ranges are used and a value greater than or equal to hex is obtained, the value is negative. If a value less than or equal to FFF hex is obtained, then the value is positive. The sign bit is the most significant bit, which combines hex to the data value. If the value is greater than or equal to hex, only the most significant bit and the active channel bits need to be masked to determine the actual data value. NOTE: L PUs with firmware release version. or later and L PUs with firmware release version. or later support this method. Use the L multiplexing example if your firmware is an earlier version. The two programs on the next page show how this can be accomplished. The first example uses magnitude plus sign (binary) and the second example uses magnitude plus sign (). The examples only show two channels. It is good to know when a value is negative, so these rungs should be placed before any other operations that use the data, such as math instructions, scaling operations, etc. lso, if stage programming instructions are being used, these rungs should be in a stage that is always active. NOTE: This logic is only needed for each channel that is using bipolar input signals. L nalog Manual, th Edition Rev. -

14 hapter : F-RT -hannel RT Input - Magnitude Plus Sign (inary) heck hannel SP V heck hannel SP V Magnitude Plus Sign () heck hannel SP V heck hannel SP V ² ² ² ² K K K K L V N KFFF V L V N KFFF V L V N KFFFFFFF V L V N KFFFFFFF V L nalog Manual, th Edition Rev. Load channel data from V-memory into the accumulator. ontact SP is always on. This instruction masks the sign bit ofthe binary data, if it is set. Without this step, negative values will not be correct so do not forget to include it. Put the actual signal value in V. Now you can use the data normally. hannel data is negative when is on(a value of -. reads as, -. is, etc.). Load channel from V-memory into the accumulator. ontact SP is always on. This instruction masks the sign bit ofthe binary data, if it is set. Without this step, negative values will not be correct so do not forget to include it. Put the actual signal value in V. Now you can use the data normally. hannel data is negative when is on(a value of -. reads as, -. is, etc.). Load channel data from V-memory into the accumulator. Remember, the data can be negative. ontact SP is always on. This instruction masks the sign bit of the data, if it is set. Without this step, negative values will not be correct so do not forget to include it. Put the actual signal value in V. Now you can use the data normally. hannel data is negative when is on(a value of -. reads as, -. is, etc.). Load channel from V-memory into the accumulator. Remember, the data can be negative. ontact SP is always on. This instruction masks the sign bit of the data, if it is set. Without this step, negative values will not be correct so do not forget to include it. Put the actual signal value in V. Now you can use the data normally. hannel data is negative when is on(a value of -. reads as, -. is, etc.).

15 hapter : F-RT -hannel RT Input Negative Temperatures s omplement for the L, L- and L PUs (inary/pointer Method) The s complement mode used for negative temperature display purposes, while at the same time using the magnitude plus sign of the temperature in a control program. The irectsoft element Signed ecimal is used to display negative numbers in s complement form. To find the absolute value of a negative number in s complement, invert the number and add as shown in the following example: V ² K Understanding the Input ssignments (Multiplexing Ladder Only) Remember that this module appears to the PU as a -point discrete input module. Use these points to obtain: n indication of which channel is active The digital representation of the analog signal Module diagnostic information L V INV K V Load negative value into the accumulator so we can convert ittoapositive value. Invert the binary pattern in the accumulator. dd. Save hannel data atv. Repeat for other channels as required. Since all input points are automatically mapped into V-memory, it is easy to determine the location of the data word that will be assigned to the module. MS V pt Input V pt Input F-RT Slot Slot Slot Slot Slot LS pt Input - MS pt Input V pt Output Y Y V it it LS L nalog Manual, th Edition Rev. -

16 hapter : F-RT -hannel RT Input When a L PU is used, the input points must start on a V-memory boundary. To use the V-memory references required for a L PU, refer to the table below. The first input address assigned to a module must be one of the inputs shown. The table also shows the V-memory addresses that correspond to these inputs. V V V V V V V V V nalog ata its The first bits represent the analog data in binary format. it Value it Value ctive hannel its The active channel bits represent the multiplexed channel selections in binary format. it it hannel roken Transmitter its (Multiplexing Ladder Methods) The broken transmitter bits are on when the corresponding RT is open. MS NOTE: The broken transmitter bits only function using the Multiplexing method. MS MS V LS = data bits V =active channel bits V LS LS =broken transmitter bits - L nalog Manual, th Edition Rev.

17 hapter : F-RT -hannel RT Input Reading Magnitude Plus Sign Values (Multiplexing) The L PU does not have the special V-memory locations that allows for automatic enabling the data transfer. Since all channels are multiplexed into a single data word, the control program must be set up to determine which channel is being read. Since the module appears as input points to the PU, it is very easy to use the active channel status bits to determine which channel is being monitored. NOTE: L PUs with firmware release version. or later required for multiplexing ladder. SP Store hannel Store hannel Store hannel Store hannel L V N KFFF V V V V RST SET RST SET RST SET RST SET Loads the complete data word into the accumulator. The V-memory location depends on the I/O configuration. See ppendix for the memory map. This instruction masks the sign bit. Without this, the values used will not be correct sodo not forget to include it. When,, and are off, channel data is stored in V. is reset to indicate that channel s value is positive. If ison, the data value represents anegative temperature. is set to indicate that channel s value is negative. When isonand and are off, channel data is stored in V. is reset to indicate that channel s value is positive. If ison, the data value represents anegative temperature. is set to indicate that channel s value is negative. When and are off and is on, channel data is stored in V. is reset to indicate that channel s value is positive. If is on, then the data value represents a negative temperature. is set to indicate that channel s value is negative. When both and are onand isoff, channel data is stored in V. is reset to indicate that channel s value is positive. If ison, the data value represents anegative temperature. is set to indicate that channel s value is negative. L nalog Manual, th Edition Rev. -

18 hapter : F-RT -hannel RT Input Reading s ompliment Values (Multiplexing) The L PU does not have the special V-memory locations that allows for automatic enabling the data transfer. Since all channels are multiplexed into a single data word, the control program must be set up to determine which channel is being read. Since the module appears as input points to the PU, it is very easy to use the active channel status bits to determine which channel is being monitored. The s complement data format may be required to correctly display bipolar data on some operator interfaces. This data format could also be used to simplify averaging a bipolar signal. To view this data format in irectsoft, select Signed ecimal. Load ata SP Store hannel Store hannel Store hannel Store hannel L V N KFFF V V V V Loads the complete data word into the accumulator. The V-memory location depends on the I/O configuration. This instruction masks the channel sign bit. When, and are off, channel data is stored in V. When isonand and are off, channel data isstored inv. When and are off and ison, channel data isstored inv. When both and are on and isoff, channel data isstored inv. Scaling the Input ata No scaling of the input temperature is required. The readings directly reflect the actual temperatures. For example: a reading of is., a reading of is -. (magnitude plus sign) and a reading of is -. ( s complement). - L nalog Manual, th Edition Rev.

19 hapter : F-RT -hannel RT Input Filtering Input Noise (L- and L PUs Only) dd the following logic to filter and smooth analog input noise in L- and L PUs. This is especially useful when using PI loops. Noise can be generated by the field device and/ or induced by field wiring. The analog value in is first converted to a binary number. Memory location V is the designated workspace in this example. The MULR instruction is the filter factor, which can be from... The example uses.. Using a smaller filter factor increases filtering. higher precision value can be used, but it is not generally needed. The filtered value is then converted back to binary and then to. The filtered value is stored in location V for use in the application program or a PI loop. NOTE: e careful not to do a multiple number conversion on a value. For example, if the pointer method is used to get the analog value, it is in and must be converted to binary. However, if the conventional method of reading analog is used and the first bits are masked, the value is already in binary and no conversion is needed. lso, if the conventional method is used, change the LL V instruction to L V. SP L V IN TOR SUR V MULR R. R V V RTO V Loads the analog signal, which isa value and has been loaded from V-memory location V, into the accumulator. ontact SP is always on. onverts the value in the accumulator to binary. Remember, this instruction is not needed ifthe analog value is originally brought in as a binary number. onverts the binary value in the accumulator to areal number. Subtracts the real number stored inlocation V from the real number inthe accumulator, and stores the result inthe accumulator. V is the designated workspace in this example. Multiplies the real number in the accumulator by. (the filter factor), and stores the result inthe accumulator. This is the filtered value. dds the real number stored in location V to the real number filtered value in the accumulator, and stores the result in the accumulator. opies the value in the accumulator to location V. onverts the real number in the accumulator toabinary value, and stores the result in the accumulator. onverts the binary value in the accumulator to a number. NOTE: The instruction is not needed for PI loop PV (loop PV is a binary number). Loads the number filtered value from the accumulator into location V to use in your application or PI loop. L nalog Manual, th Edition Rev. -

20 hapter : F-RT -hannel RT Input Notes - L nalog Manual, th Edition Rev.