F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input In This Chapter. . . . — Module Specifications — Setting the Module Jumpers — Connecting the Field Wiring — Module Operation — Writing the Control Program 2 2--2 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input F2--04AD--1, (L) 4-Ch. Current Input Module Specifications F2--04AD--1 The F2--04AD--1 analog Input module provides several hardware features. S On-board 250 ohm, 1/2 watt precision resistors provide substantial over-current-protection for 4--20mA current loops. S Analog inputs are optically isolated from the PLC logic. S The module has a removable terminal block so the module can be easily removed or changed without disconnecting the wiring. S With a DL240/250--1/260 CPU, you can read all four channels in one scan. S On-board active analog filtering and RISC-like microcontroller provide digital signal processing to maintain precision analog measurements in noisy environments. F2-04AD-1 IN ANALOG 4CH F2--04AD--1 10--30VDC 5mA 0V +24V CH1-CH1+ CH2-CH2+ CH3-CH3+ CH4-CH4+ ANALOG IN 4--20mA F2-04AD-1L F2--04AD--1L (Obsolete) NOTE: In 2009 the F2--04AD--1L was discontinued. A re--designed F2--04AD--1 was released at the same time which can be powered by either 12 VDC or 24VDC input power supplies. This new module is a direct replacement for prior F2--04AD--1 and all F2--04AD--1L modules. The new module is a single circuit board design and the jumper link locations are different. See Setting the Module Jumpers on page 2--5. Also, some specifications were changed on page 2--3. Otherwise, the re--designed module functions the same as the prior designs. IN F2--04AD--1 18--26.4VDC 80mA 0V +12V CH1-CH1+ CH2-CH2+ CH3-CH3+ CH4-CH4+ ANALOG IN 4--20mA DL205 Analog Manual 7th Ed. Rev. B 4/10 ANALOG 4CH F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Input Specifications 2--3 These tables provide specifications for both the F2--04AD--1 and F2--04AD--1L Analog Input Modules (all specifications are the same for both modules except for the input voltage requirements). Review these specifications to make sure the module meets your application requirements. 4, single ended (one common) Input Range 4 to 20 mA current Resolution 12 bit (1 in 4096) Step Response 4.9 ms (*4.0 ms) to 95% of full step change Crosstalk --80 dB, 1/2 count maximum Active Low-pass Filtering --3 dB at 120Hz (*80Hz), 2 poles (--12 dB per octave) Input Impedance 250Ω 0.1%, ½W current input Absolute Maximum Ratings --40 mA to +40 mA, mA current input Converter type Successive approximation Linearity Error (End to End) 1 count (0.025% (0 025% of full scale) maximum Input Stability 1 count Full Scale Calibration Error (Offset error not included) 12 counts maximum, maximum @ 20mA current input Offset Calibration Error 7 counts maximum, maximum @ 4mA current input Maximum Inaccuracy .5% @ 25C 25 C (77F) (77 F) .65% 0 to 60_C (32 to 140F) Accuracy y vs. Temperature p 50 ppm/ ppm/_C C maximum full scale calibration (including maximum offset change) Recommended Fuse (external) 0 032 A, 0.032 A Series 217 fast-acting, fast-acting current inputs One count in the specification table is equal to one least significant bit of the analog data value (1 in 4096). PLC Update Rate 1 channel per scan maximum (DL230 CPU) 4 channels per scan maximum (DL240/250--1/260 CPU) Digital Inputs Input points required 12 binary data bits, 2 channel ID bits, 2 diagnostic bits 16 point (X) input module Power Budget Requirement 100 mA (*50 mA) maximum, maximum 5 VDC (supplied by base) External Power Supply 5mA (*80mA) max., 10 (*18) to 30 VDC (F2-04AD-1) 90mA maximum, 10 to 15 VDC (F2-04AD-1L) Operating Temperature 0 to 60_ C (32 to 140 F) Storage Temperature -20 to 70_ C (-4 to 158 F) Relative Humidity 5 to 95% (non-condensing) Environmental air No corrosive gases permitted Vibration MIL STD 810C 514.2 Shock MIL STD 810C 516.2 Noise Immunity NEMA ICS3--304 * Values in parenthesis with an asterisk are for older modules with two circuit board design and date codes 0609F3 or previous. Values not in parenthesis are for single circuit board models with date code 0709G or above. Analog Input Configuration Requirements Appears as a 16-point discrete input module and can be installed in any slot of a DL205 system. The available power budget and discrete I/O points are the limiting factors. Check the user manual for your particular model of CPU and I/O base for more information regarding power budget and number of local, local expansion or remote I/O points. DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input Number of Channels 2--4 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Special Placement Requirements (DL230 and Remote I/O Bases) Even though the module can be placed in any slot, it is important to examine the configuration if you are using a DL230 CPU. As you can see in the section on writing the program, you use V-memory locations to extract the analog data. If you place the module so that the input points do not start on a V-memory boundary, the instructions cannot access the data. This also applies when placing this module in a remote base using a D2--RSSS in the CPU slot. F2-04AD-1 F2--04AD--1, (L) 4-Ch. Current Input Correct! Slot 0 Slot 1 8pt Input 8pt Input Slot 2 16pt Input 16pt Input 16pt Output X0 -X7 X10 -X17 X20 -X37 X40 -X57 Y0 -Y17 V40400 Data is correctly entered so input points start on a V-memory boundary. Slot 3 Slot 4 V40402 V40401 MSB LSB X 3 7 Incorrect X 2 0 F2-04AD-1 Slot 0 Slot 1 Slot 2 Slot 3 8pt Input 16pt Input 16pt Input 16pt Input Slot 4 16pt Output X0 -X7 X10 -X27 X30 -X47 X50 -X67 Y0 -Y17 Data is split over two locations, so instructions cannot access data from a DL230. MSB V40401 LSB X X 3 2 0 7 X 3 7 X 2 0 MSB V40400 LSB X X 1 7 0 X 1 7 X 0 To use the V-memory references required for a DL230 CPU, the first input address assigned to the module must be one of the following X locations. The table also shows the V-memory addresses that correspond to these X locations. X X0 X20 X40 V V40400 V40401 V40402 V40403 V40404 V40405 V40406 V40407 DL205 Analog Manual 7th Ed. Rev. B 4/10 X60 X100 X120 X140 X160 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input 2--5 Setting the Module Jumpers Selecting the Number of Channels Jumper Location on Modules Having Date Code 0609F3 and Previous (Two Circuit Board Design) +1 For example, to select all 4 channels (1 -- 4), leave both jumpers installed. To select channel 1, remove both jumpers. Jumper Location on Modules Having Date Code 0709G and Above (Single Circuit Board Design) +2 +1 +2 Jumper +1 These jumpers are located on the motherboard, the one with the black D-shell style backplane connector. DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input There are two jumpers, labeled +1 and +2, that are used to select the number of channels that will be used. See the figures below to find the jumpers on your module. The module is set from the factory for four channel operation. Any unused channels are not processed, so if you only select channels 1 thru 3, channel 4 will not be active. The following table shows how to use the jumpers to select the number of channels. No. of Channels +1 +2 1 No No 1, 2 Yes No 1, 2, 3 No Yes 1, 2, 3, 4 Yes Yes 2--6 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Connecting the Field Wiring F2--04AD--1, (L) 4-Ch. Current Input Wiring Guidelines User Power Supply Requirements Your company may have guidelines for wiring and cable installation. If so, you should check those before you begin the installation. Here are some general things to consider: S Use the shortest wiring route whenever possible. S Use shielded wiring and ground the shield at the transmitter source. Do not ground the shield at both the module and the source. S Do not run the signal wiring next to large motors, high current switches, or transformers. This may cause noise problems. S Route the wiring through an approved cable housing to minimize the risk of accidental damage. Check local and national codes to choose the correct method for your application. The module requires at least one field-side power supply. You may use the same or separate power sources for the module supply and the current transmitter supply. The F2-04AD-1 module requires 18--30VDC, at 80 mA. The DL205 bases have built-in 24 VDC power supplies that provide up to 300mA of current. You may use this with F2-04AD-1 modules instead of a separate supply if you are using only a couple of analog modules. It is desirable in some situations to power the transmitters separately in a location remote from the PLC. This will work as long as the transmitter supply meets the voltage and current requirements, and the transmitter’s minus (--) side and the module supply’s minus (--) side are connected together. WARNING: If you are using the 24 VDC base power supply, make sure you calculate the power budget. Exceeding the power budget can cause unpredictable system operation that can lead to a risk of personal injury or damage to equipment. The DL205 base has a switching type power supply. As a result of switching noise, you may notice 3--5 counts of instability in the analog input data if you use the base power supply. If this is unacceptable, you should try one of the following: 1. Use a separate linear power supply. 2. Connect the 24VDC common to the frame ground, which is the screw terminal marked “G” on the base. By using these methods, the input stability is rated at 1 count. The F2-04AD-1L module requires 10--15VDC, at 90 mA and must be powered by a separate power supply. DL205 Analog Manual 7th Ed. Rev. B 4/10 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Current Loop Transmitter Impedance 2--7 Standard 4 to 20 mA transmitters and transducers can operate from a wide variety of power supplies. Not all transmitters are alike and the manufacturers often specify a minimum loop or load resistance that must be used with the transmitter. The F2-04AD-1, (L) provides 250 ohm resistance for each channel. If your transmitter requires a load resistance below 250 ohms, you do not have to make any adjustments. However, if your transmitter requires a load resistance higher than 250 ohms, you need to add a resistor in series with the module. Consider the following example for a transmitter being operated from a 30 VDC supply with a recommended load resistance of 750 ohms. Since the module has a 250 ohm resistor, you need to add an additional resistor. R ≥ 500 R -- resistor to add Tr -- Transmitter Requirement Mr -- Module resistance (internal 250 ohms) Two-wire Transmitter + -DC Supply +30V 0V Module Channel 1 R CH1+ CH1-0V 250 ohms DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input R = Tr − Mr R = 750 − 250 2--8 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Wiring Diagram The F2--04AD--1, (L) module has a removable connector to make wiring easier. Simply squeeze the top and bottom retaining clips and gently pull the connector from the module. Use the following diagram to connect the field wiring. The diagram shows separate module and transmitter power supplies. If you desire to use only one field-side supply, just combine the supplies’ positive (+) terminals into one node, and remove the transmitter supply. Module Supply See NOTE 5 10--15 VDC 18--30 VDC + -- Internal Module Wiring See NOTE 1 0 VDC See NOTE 5 +24 VDC -- + -CH1 4--wire + 4--20mA Transmitter CH1-- CH2-- -CH4 2-wire + 4--20mA Transmitter 0V F2--04AD--1 CH3-- Fuse 250 ohms CH3+ CH4-- Fuse 10--30VDC 5mA 250 ohms CH2+ -- CH3 2-wire + 4--20mA Transmitter +5V +15V --15V 250 ohms CH4+ Fuse Analog Switch -CH2 3--wire + 4--20mA Transmitter 250 ohms ANALOG 4CH CH1+ Fuse + IN DC to DC Converter F2--04AD--1, (L) 4-Ch. Current Input Typical User Wiring A to D Converter 0V +24V CH1-CH1+ CH2-CH2+ CH3-CH3+ CH4-CH4+ ANALOG IN 4--20mA + -18-30VDC Supply Transmitter Supply OV 24 Volts Model Shown NOTE 1: Shields should be grounded at the signal source. NOTE 2: More than one external power supply can be used, provided all the power supply commons are connected. NOTE 3: A Series 217, 0.032A fast-acting fuse is recommended for 4--20 mA current loops. NOTE 4: If the power supply common of an external power supply is not connected to 0VDC on the module, then the output of the external transmitter must be isolated. To avoid “ground loop” errors, recommended 4--20 mA transmitter types are: 2 or 3 wire: Isolation between input signal and power supply. 4 wire: Isolation between input signal, power supply, and 4--20mA output. NOTE 5: Use 10--15VDC for F2-04AD-1L Use 18--30VDC for F2-04AD-1 DL205 Analog Manual 7th Ed. Rev. B 4/10 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input 2--9 Module Operation Channel Scanning Sequence for a DL230 CPU (Multiplexing) Scan System With DL230 CPU Read Inputs Execute Application Program Read the data Store data Scan N Channel 1 Scan N+1 Channel 2 Scan N+2 Channel 3 Scan N+3 Channel 4 Scan N+4 Channel 1 Write to Outputs DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input Before you begin writing the control program, it is important to take a few minutes to understand how the module processes and represents the analog signals. The module can supply different amounts of data per scan, depending on the type of CPU you are using. The DL230 can obtain one channel of data per CPU 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 1. Unused channels are not processed, so if you select only two channels, then each channel will be updated every other scan. The multiplexing method can also be used for the DL240/250--1 and DL260 CPUs. 2--10 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Channel Scanning Sequence for a DL240, DL250--1 or or DL260 CPU (Pointer Method) If you are using a DL240/250--1/260 CPU , you can obtain all four channels of input data in one scan. This is because the DL240/250--1/260 CPU supports special V-memory locations that are used to manage the data transfer. This is discussed in more detail in the section on Writing the Control Program. Scan System With DL240/250--1/260 CPU F2--04AD--1, (L) 4-Ch. Current Input Read Inputs Execute Application Program Read the data Store data Scan N Ch 1, 2, 3, 4 Scan N+1 Ch 1, 2, 3, 4 Scan N+2 Ch 1, 2, 3, 4 Scan N+3 Ch 1, 2, 3, 4 Scan N+4 Ch 1, 2, 3, 4 Write to Outputs Analog Module Updates Even though the channel updates to the CPU are synchronous with the CPU scan, the module asynchronously monitors the analog transmitter signal and converts the signal to a 12-bit binary representation. This enables the module to continuously provide accurate measurements without slowing down the discrete control logic in the RLL program. For the vast majority of applications, the values are updated much faster than the signal changes. However, in some applications, the update time can be important. The module takes approximately 4 milliseconds to sense 95% of the change in the analog signal. Note, this is not the amount of time required to convert the signal to a digital representation. The conversion to the digital representation takes only a few microseconds. Many manufacturers list the conversion time, but it is the settling time of the filter that really determines the update time. DL205 Analog Manual 7th Ed. Rev. B 4/10 2--11 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Understanding the Input Assignments You may recall the F2-04AD-1, (L) module requires 16 discrete input points in the CPU. You can use these points to obtain: S an indication of which channel is active S the digital representation of the analog signal S module diagnostic information Since all input points are automatically mapped into V-memory, it is very easy to determine the location of the data word that will be assigned to the module. F2-04AD-1 Slot 1 Slot 2 Slot 3 8pt Input 8pt Input 16pt Input 16pt Input X0 -X7 X10 -X17 X20 -X37 X40 -X57 V40400 MSB X XXX 3 3 3 3 7 6 5 4 Analog Data Bits V40402 V40401 Data Bits Slot 4 16pt Output Y0 -Y17 V40500 LSB X 2 0 Within these word locations, the individual bits represent specific information about the analog signal. The first twelve bits represent the analog V40401 data in binary format. MSB LSB Bit Value Bit Value 0 1 6 64 1 1 1 1 1 19 8 7 6 5 4 3 2 1 0 1 2 7 128 5 4 3 21 0 2 4 8 256 3 8 9 512 = data bits 4 16 10 1024 5 32 11 2048 DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input Slot 0 2--12 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input F2--04AD--1, (L) 4-Ch. Current Input Active Channel Indicator Inputs Module Diagnostic Inputs Two of the inputs are binary-encoded to indicate the active channel (remember, the V-memory bits are mapped directly to discrete inputs). The inputs are automatically turned on and off to indicate the active channel for each scan. Scan X35 X34 Channel N Off Off 1 N+1 Off On 2 N+2 On Off 3 N+3 On On 4 N+4 Off Off 1 The last two inputs are used for module diagnostics. Module Busy — The first diagnostic input (X36 in this example) indicates a “busy” condition. This input will always be active on the first PLC scan, to tell the CPU the analog data is not valid. After the first scan, the input usually only comes on when extreme environmental (electrical) noise problems are present. The programming examples in the next section shows how you can use this input. The wiring guidelines shown earlier in this chapter provide steps that can help reduce noise problems. V40401 MSB LSB X X 3 3 5 4 X 2 0 = channel inputs V40401 MSB LSB X X 3 3 7 6 X 2 0 = diagnostic inputs Note: When using the pointer method, the value placed into the V-memory location will be 8000 instead of the bit being set. Channel Failure — The last diagnostic input (X37 in this example) indicates the analog channel is not operating. For example, if the 24 VDC input power is missing or if the terminal block is loose, the module will turn on this input point. The module also returns a data value of zero to further indicate there is a problem. The next section, Writing the Control Program, shows how you can use these inputs in your control program. Module Resolution Since the module has 12-bit resolution, the analog signal is converted into 4096 counts ranging from 0 -- 4095 (212). For example, a 4mA signal would be 0 and a 20mA signal would be 4095. This is equivalent to a a binary value of 0000 0000 0000 to 1111 1111 1111, or 000 to FFF hexadecimal. The diagram shows how this relates to the signal range. Each count can also be expressed in terms of the signal level by using the equation shown. DL205 Analog Manual 7th Ed. Rev. B 4/10 4 -- 20mA 20mA 4mA 0 4095 Resolution = H − L 4095 H = high limit of the signal range L = low limit of the signal range 16mA / 4095 = 3.907uA per count F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input 2--13 Writing the Control Program Reading Values: Pointer Method and Multiplexing 230 240 250-- 1 260 NOTE: DL250 CPUs with firmware release version 1.06 or later support this method. If you must use the DL230 example, module placement in the base is very important. Review the section earlier in this chapter for guidelines. The example program shows how to setup these locations. Place this rung anywhere in the ladder program, or in the initial stage if you are using stage programming instructions. This is all that is required to read the data into V-memory locations. Once the data is in V-memory you can perform math on the data, compare the data against preset values, and so forth. V2000 is used in the example but you can use any user V-memory location. In this example the module is installed in slot 2. You should use the V-memory locations for your module placement. The pointer method automatically converts values to BCD (depending on the LD statement in the ladder logic). SP0 LD K 04 00 - or - LD K 84 00 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 (i.e. 0=BCD, 8=Binary), the LSN selects the number of channels (i.e. 1, 2, 3, or 4). The binary format is used for displaying data on some operator interfaces. The DL230/240 CPUs do not support binary math functions, whereas the DL250 does. OUT V7662 Special V-memory location assigned to slot 2 that contains the number of channels to scan. LDA O2000 This loads an octal value for the first V-memory location that will be used to store the incoming data. For example, the O2000 entered here would designate the following addresses. Ch1 -- V2000, Ch2 -- V2001, Ch3 -- V2002, Ch 4 -- V2003 OUT V7672 The octal address (O2000) is stored here. V7672 is assigned to slot 2 and acts as a pointer, which means the CPU will use the octal value in this location to determine exactly where to store the incoming data. DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input Pointer Method There are two methods of reading values: S The pointer method S Multiplexing You must use the multiplexing method when using a DL230 CPU. You must also use the multiplexing method with remote I/O modules (the pointer method will not work). You can use either method when using DL240, DL250--1 and DL260 CPUs, but for ease of programming it is strongly recommended that you use the pointer method. The DL205 series has special V-memory locations assigned to each base slot that greatly simplify the programming requirements. These V-memory locations allow you to: S specify the data format S specify the number of channels to scan S specify the storage locations 2--14 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input The tables below show the special V-memory locations used by the DL240, DL250--1 and DL260 for the CPU base and local expansion base I/O slots. Slot 0 (zero) is the module next to the CPU or D2--CM module. Slot 1 is the module two places from the CPU or D2--CM, and so on. Remember, the CPU only examines the pointer values at these locations after a mode transition. Also, if you use the DL230 (multiplexing) method, verify that these addresses in the CPU are zero. The Table below applies to the DL240, DL250--1 and DL260 CPU base. CPU Base: Analog Input Module Slot-Dependent V-memory Locations F2--04AD--1, (L) 4-Ch. Current Input Slot 0 1 2 3 4 5 6 7 No. of Channels V7660 V7661 V7662 V7663 V7664 V7665 V7666 V7667 Storage Pointer V7670 V7671 V7672 V7673 V7674 V7675 V7676 V7677 The Table below applies to the DL250--1 or DL260 expansion base 1. Expansion Base D2--CM #1: Analog Input Module Slot-Dependent V-memory Locations Slot 0 1 2 3 4 5 6 7 No. of Channels V36000 V36001 V36002 V36003 V36004 V36005 V36006 V36007 Storage Pointer V36010 V36011 V36012 V36013 V36014 V36015 V36016 V36017 The Table below applies to the DL250--1 or DL260 expansion base 2. Expansion Base D2--CM #2: Analog Input Module Slot-Dependent V-memory Locations Slot 0 1 2 3 4 5 6 7 No. of Channels V36100 V36101 V36102 V36103 V36104 V36105 V36106 V36107 Storage Pointer V36110 V36111 V36112 V36113 V36114 V36115 V36116 V36117 The Table below applies to the DL260 CPU expansion base 3. Expansion Base D2--CM #3: Analog Input Module Slot-Dependent V-memory Locations Slot 0 1 2 3 4 5 6 7 No. of Channels V36200 V36201 V36202 V36203 V36204 V36205 V36206 V36207 Storage Pointer V36210 V36211 V36212 V36213 V36214 V36215 V36216 V36217 The Table below applies to the DL260 CPU expansion base 4. Expansion Base D2--CM #4: Analog Input Module Slot-Dependent V-memory Locations Slot 0 1 2 3 4 5 6 7 No. of Channels V36300 V36301 V36302 V36303 V36304 V36305 V36306 V36307 Storage Pointer V36310 V36311 V36312 V36313 V36314 V36315 V36316 V36317 DL205 Analog Manual 7th Ed. Rev. B 4/10 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Reading Values (Multiplexing) 230 240 250-- 1 260 2--15 The DL230 CPU does not have the special V-memory locations that allow you to automatically enable the data transfer. Since all channels are multiplexed into a single data word, the control program must be setup to determine which channel is being read. Since the module appears as X input points to the CPU, it is very easy to use the active channel status bits to determine which channel is being monitored. Note, this example is for a module installed as shown in the previous examples. The addresses used would be different if the module was installed in a different I/O arrangement. You can place these rungs anywhere in the program, or if you are using stage programming place them in a stage that is always active. ANDD KFFF Store Channel 1 X36 X34 X35 Store Channel 2 X36 X34 X35 Store Channel 3 X36 X34 X35 Store Channel 4 X36 X34 X35 Loads the complete data word into the accumulator. The V-memory location depends on the I/O configuration. See Appendix A for the memory map. This instruction masks the channel identification bits. Without this, the values used will not be correct so do not forget to include it. BCD It is usually easier to perform math operations in BCD, so it is best to convert the data to BCD immediately. You can leave out this instruction if your application does not require it. OUT V2000 When the module is not busy and X34 and X35 are off, channel 1 data is stored in V2000. OUT V2001 When X34 is on and X35 is off, channel 2 data is stored in V2001. OUT V2002 OUT V2003 When X34 is off and X35 is on, channel 3 data is stored in V2002. When both X34 and X35 are on, channel 4 data is stored in V2003. DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input Load Data when Module is not busy X36 LD V40401 2--16 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Single Channel Selected Since you do not have to determine which channel is selected, the single channel program is even more simple. Store Channel 1 when Module is not busy X36 X34 X35 LD V40401 Loads the complete data word into the accumulator. The V-memory location depends on the I/O configuration. See Appendix A for the memory map. ANDD KFFF F2--04AD--1, (L) 4-Ch. Current Input BCD OUT V2000 Analog Power Failure Detection This instruction masks the channel identification bits. Without this, the values used will not be correct so do not forget to include it. It is usually easier to perform math operations in BCD, so it is best to convert the data to BCD immediately. You can leave out this instruction if your application does not require it. When the module is not busy and X34 and X35 are off, channel 1 data is stored in V2000. The Analog module has an on-board processor that can diagnose analog input circuit problems. You can easily create a simple ladder rung to detect these problems. This rung shows an input point that would be assigned if the module was installed as shown in the previous examples. A different point would be used if the module was installed in a different I/O arrangement. Multiplexing method V2000 K0 X37 = C1 OUT V-memory location V2000 holds channel 1 data. When a data value of zero is returned and input X37 is on, then the analog circuitry is not operating properly. Pointers method V2000 K8000 = Scaling the Input Data Most applications usually require measurements in engineering units, which provides more meaningful data. This is accomplished by using the conversion formula shown. You may have to make adjustments to the formula depending on the scale you choose for the engineering units. C1 OUT V-memory location V2000 holds channel 1 data. When a data value of 8000 is returned, then the analog circuitry is not operating properly. Units = A H − L 4095 H = High limit of the engineering unit range L = Low limit of the engineering unit range A = Analog value (0 -- 4095) For example, if you wanted to measure pressure (PSI) from 0.0 to 99.9 then you would have to multiply the analog value by 10 in order to imply a decimal place when you view the value with the programming software or a handheld programmer. Notice how the calculations differ when you use the multiplier. DL205 Analog Manual 7th Ed. Rev. B 4/10 2--17 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Analog Value of 2024, slightly less than half scale, should yield 49.4 PSI Example without multiplier Example with multiplier Units = A H − L 4095 Units = 10 A H − L 4095 Units = 2024 100 − 0 4095 Units = 20240 100 − 0 4095 Units = 49 Units = 494 Handheld Display Handheld Display V 2001 V 2000 0000 0494 This value is more accurate The following example shows how you would write the program to perform the engineering unit conversion. This example assumes you have BCD data loaded into the appropriate V-memory locations using instructions that apply for the model of CPU you are using. Note: this example uses SP1, which is always on. You could also use an X, C, etc. permissive contact. SP1 LD V2000 When SP1 is on, load channel 1 data to the accumulator. MUL K1000 Multiply the accumulator by 1000 (to start the conversion). DIV K4095 Divide the accumulator by 4095. OUT V2010 Analog and Digital Value Conversions Store the result in V2010. Sometimes it is useful to be able to quickly convert between the signal levels and the digital values. This is especially helpful during machine startup or troubleshooting. The following table provides formulas to make this conversion easier. Range 4 to 20mA If you know the digital value... If you know the analog signal level... A = 16D + 4 4095 D = 4095 (A − 4) 16 For example, if you have measured the signal as 10mA, you can use the formula to easily determine the digital value that will be stored in the V-memory location that contains the data. D = 4095 (A − 4) 16 4095 D= (10mA – 4) 16 D = (255.93) (6) D = 1536 DL205 Analog Manual 7th Ed. Rev. B 4/10 F2--04AD--1, (L) 4-Ch. Current Input V 2001 V 2000 0000 0049 2--18 F2-04AD-1, F2-04AD-1L 4-Channel Analog Current Input Filtering Input Noise (DL250--1, DL260 CPU Only) F2--04AD--1, (L) 4-Ch. Current Input 230 240 250-- 1 260 Add the following logic to filter and smooth analog input noise in DL250--1 and DL260 CPUs. This is especially useful when using PID loops. Noise can be generated by the field device and/or induced by field wiring. The analog value in BCD is first converted to a binary number because there is not a BCD-to-real conversion instruction. Memory location V1400 is the designated work space in this example. The MULR instruction is the filter factor, which can be from 0.1 to 0.9. The example uses 0.2. A smaller filter factor increases filtering. You can use a higher precision value, but it is not generally needed. The filtered value is then converted back to binary and then to BCD. The filtered value is stored in location V1402 for use in your application or PID loop. NOTE: Be careful not to do a multiple number conversion on a value. For example, if you are using the pointer method to get the analog value, it is in BCD and must be converted to binary. However, if you are using the conventional method of reading analog and are masking the first twelve bits, then it is already in binary and no conversion using the BIN instruction is needed. SP1 LD V2000 BIN BTOR Converts the BCD value in the accumulator to binary. Remember, this instruction is not needed if the analog value is originally brought in as a binary number. Converts the binary value in the accumulator to a real number. SUBR V1400 Subtracts the real number stored in location V1400 from the real number in the accumulator, and stores the result in the accumulator. V1400 is the designated workspace in this example. MULR R0.2 Multiplies the real number in the accumulator by 0.2 (the filter factor), and stores the result in the accumulator. This is the filtered value. ADDR V1400 Adds the real number stored in location V1400 to the real number filtered value in the accumulator, and stores the result in the accumulator. OUTD V1400 RTOB BCD OUT V1402 DL205 Analog Manual 7th Ed. Rev. B 4/10 Loads the analog signal, which is a BCD value and has been loaded from V-memory location V2000, into the accumulator. Contact SP1 is always on. Copies the value in the accumulator to location V1400. Converts the real number in the accumulator to a binary value, and stores the result in the accumulator. Converts the binary value in the accumulator to a BCD number. Note: The BCD instruction is not needed for PID loop PV (loop PV is a binary number). Loads the BCD number filtered value from the accumulator into location V1402 to use in your application or PID loop.
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