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Siemens S7-300/400 PLC Closed-loop control module

1, FM 355 closedloop control module
FM 355 closedloop control channel 4, used for pressure, flow, liquid level control, optimum temperature control and PID algorithms. FM 355C analog output is 4 fracture of continuous controller, FM 355 s is 8 digital output point step controllers or pulse. CPU FM 355 people after a disruption or failure will continue to operate, control procedure stored in a module.
FM 355 4 analog input is used to collect analog values and feed-forward control value, additional analog inputs for thermocouple temperature compensation. Can use a variety of sensors such as thermocouples, Pt100, thermal resistance, voltage and current sensors. FM 355 closedloop control of 4 separate channels, you can implement a custom control, cascade control, proportional control and 3component control, using several controllers can be integrated into one system. Automatic, manual, safety, follow, back this way. 12 for the resolution of the sampling time of 20~100ms,14 for 100~500ms resolution.
Self-tuning temperature control algorithm in m fast, starts automatically when the set point change is greater than 12% liberalization; configuration software package can be used to optimize PID control algorithm.
Defective CPU or CPU to stop working is controller can control independently. In: backup function set adjustable security settings or security control variables. You can read and modify all the parameters of fuzzy temperature controller, or online to modify other parameters.

2, FM 355-2 closed-loop control module
FM 355-2 is suitable for temperaturecontrolled 4channel closedloop control module, you can easily realize online automatic temperature control, including control of heating and cooling, and combination control of heating and cooling. FM 355-2C is continuous controller has 4 analog outputs, FM 355-2S is 8 digital output of the step or pulse controller. CPU FM 355-2 after a disruption or failure is still able to run.

3, FM 455 closedloop control module
12-bit resolution sampling time for 20~180ms,14 100~1700ms (associated with the number of actual use of the analog input), there are 16 digital inputs.

4, FM 458-1DP application module
FM 458-1DP is designed for a free closedloop attitude control, and 300 block of library functions and CFC continuous function chart graphical configuration software, with a PROFIBUS-DP interface.
FM 458-1DP basic modules can perform a calculation, the openloop and closedloop control, I/O and communication modules can be extended by extension.
EXM 438-1 I/O expansion module is an optional plug-in for FM458-1DP extension module for reading signals and output requirements. Digital/analog input/output module, incremental and absolute encoders can be connected, there are 4 two 12-bit analog output.
EXM 448 communications is the optional FM 458-1DP insert the expansion module expansion module. You can use PROFIBUS-DP or SIMOLINK for high speed communication, with a spare slot, you can insert MASTERDRIVES optional modes, used to establish a SIMOLINK optical fiber communication.
FM 458-1DP and some attachment interface modules, including digital input, digital output and program storage modules.

EM235 module DIP switches selection

1, switch 6 on/off button to divide the table into two States unipolar/bipolar two full scale input. SW6=ON, select the unipolar; SW6=OFF, select dual polarity.

2, switches 4 and 5 Select gain. SW4 and SW5 3 combinations, namely SW4=ON,SW5=OFF;SW4= OFF,SW5=ON;SW4= OFF,SW5=OFF. A case study of unipolar, when SW4=ON,SW5=OFF, full scale input 0 to 50mV,0 to 100mV when SW4=OFF,SW5=ON; full scale input 0 to 500mV,0 to 1V; if SW4= OFF,SW5=OFF, full scale input 0 to 5V,0 to 20mA,0 to 10V. It is easy to see, SW4= OFF,SW5=OFF corresponding to a current or voltage DIP switch full range input is combined with the first two DIP switches correspond to the current or voltage full scale input into 100 times-times, 10 times. Switch 4 and 5 Select gain *100,*10,*1.

3, select attenuation switches 1,2 and 3. SW3 3 combinations and SW1,SW2, SW1=ON,SW2=OFF,SW3=OFF;SW1= OFF,SW2=ON,SW3=OFF;SW1= OFF,SW2=OFF,SW3=ON, respectively. Users who use the EM235 module knows that unipolar analog signal range is 0-32000, bipolar analog signal range is -32000-+32000, but in fact this value and gain as well as a full range input voltage between attenuation coefficients of conversion. Positive and negative 2.5V to the full range of bipolar input, positive and negative 5V, 10V positive and negative, for example, SW1= OFF,SW2=OFF,SW3=ON corresponding to positive and negative 10V full scale input is combined with the first two DIP switches correspond to the positive and negative 2.5V, plus or minus 4 times, twice times the 5V voltage relationship. So when the attenuation coefficient is 0.2 select DIP switch SW1= OFF,SW2=OFF,SW3=ON; when the attenuation coefficient is 0.4 select DIP switch SW1= OFF,SW2=ON,SW3=OFF; select DIP switch when the attenuation coefficient of 0.8 SW1=ON,SW2=OFF,SW3=OFF


Siemens 200 PLC analog input/output

Analog input/output universal conversion formula you can use the following conversion:
Ov = [(Osh – Osl)*(Iv – Isl)/(Ish – Isl)] + Osl

Of which:
Ov: conversion results
Iv: conversion objects
Osh: conversion result limit
Osl: conversion results lower limit
Ish: conversion limit
Isl: conversion of lower limit

STEP 7-Micro/WIN Programming Tips (Micro/WIN programming skills) Tip38 about how to achieve the conversion routines.
For convenience of users, are now exporting it as custom orders in the Micro/WIN programming software that users can add to their application.

Note: this instruction library/the author and owner of the software‘s functionality and compatibility does not take any responsibility. Risk of using the software by the user themselves. Because it is free, so it does not provide any warranty, error correction and hotline support, users do not have to contact Siemens technical support and services.

In this library, analog input to the subroutine Scale_I_to_R can be used to S7-200 internal data conversion subroutine Scale_R_I can be used for internal data conversion to analog output.
Add instruction library

Note: adding custom commands library, you need to close the Edit Library instruction project, established a new project. If you are adding a library instruction, don’t need no different from other sources.

The first step: in the Micro/WIN File (file) menu, select Add/Remove Libraries (Adding/removing instructions) commands or Libraries in the command tree (repertoire) branch, click the right mouse button, select the Add/Remove Libraries
Appears in the Add/Remove dialog box has been integrated in the native Micro/WIN of userdefined instructions.

Second step: Add (add) button, select the newly defined library file path. Userdefined library is automatically added to the Micro/WIN command Libraries under the branches of a tree.
By default, Micro/WIN to find directive file under the path in Figure 8. Users can also specify a different path. But note that libraries should be maintained in a non-removable media, if you specified a removable hard disk, the hard disk is not library not found error occurs when. Users are advised to use the default settings.

PLC Timer Three basic usage

Basic usage of timers

(1) TC

Description: X0 after 2s, Y0

(2) loss delay fault

Figure 3 power failure delays broken ladder diagram and sequence diagram
Note: when X0 is ON, the normally open contact closure, Y0 connected and self-preservation; when X0 is off, the timer start time delay when X0 when time reaches the time timer setting is removed, Y0 from ON to OFF, realize the loss of delay.
(3) the timer reset circuit

(4) attention to process analysis: X0 connect 1S,T0 ON,Y0State output for the ON,T0 is ON the normally closed contact, T0,Y0 changed its status to OFF. When the X0 is ON, and after a scan cycle, repeat the previous state.

FX series PLC N:N network

FX1N series PLC respectively above the programming port cover plate removed, insert FX1N-485-BD Communications Board seats, according to the following diagram wiring N:N network.

· N:N FX series network features, among the PLC network communication without programming, can be realized through simple settings between each PLC status or the value of shares.

When wiring note shielded twisted-pair cable, at 300 meters without matching resistor.

The following three FX1N series PLC, for example, briefly the N:N FX series network usage.

Connect 1# from X0, the main station Y0 absorbs

Connect 1# from X1, 2# from Y0 absorbs

Connect 2# enter X0, then the stand Y1

Connect 2# from X1, 1# from Y0 absorbs

Mitsubishi FX2N PLC instructions- four-storey elevator control system

1~4 the stairs outside the request button, FU, FD;
1~4 floor SQ1~SQ4 floor signals;
In the boot button on the control panel signals;
Elevator door opening and closing limit switch.
Output signal:
Lifting light,
Elevator lift AC contactor KM1~KM2,
Elevator door AC contactor KM3~KM4,
The Bell.
1. upon the request 1-4 outside staircase and elevator operation status timely response:
Increase process, floor upstairs along the request, stop and open the door, otherwise no action;
Descent, floors downstairs along the request, stop and open the door, if not action.
2. Upon request of the compartments on the Control Panel, lift passengers to the appropriate layer.
3. Elevator travel time less than 10S, otherwise stop the ladder and alarms, notify maintenance personnel to economically disadvantaged.
4. Lifts open and close time of less than 3S.
5. Ladder on the door waiting for passengers, 5S closes automatically after.
6. If passengers open 5S press close button, the elevator door.
7. Request button to reset.

Mitsubishi PLC PLS sum PLF directive

PLS (Pulse): rising differential output directive.
PLF: falling edge of differential output directive.
PLS and PLF command can only be used for the output relays and auxiliary relays (does not include special auxiliary relays). M0 in the figure only in the X0 normally open from open to close (X0 rising edge) when a scan cycle for ON,M1 only on X0 normally open contact connected become disconnected (X0 the falling edge) _ when a scan cycle is ON.
When the PLC from RUN to STOP, and then from STOP to RUN when its input signal still is ON,PLS M0 instruction will output a pulse. However, if you use the battery backup (latches) the auxiliary relays instead of M0, PLS order in this case no output pulses.

PLC pulse differential instruction using examples

Impulsive differential instruction can be used to test the rising and falling edge of the input pulse, when conditions are met, a narrow pulse signal output. PLS, PLF two instructions.
1 PLS instructions
PLS order known as the rising edge of impulsive differential instruction. Its functions are: when a rising edge of the input pulse signal is detected, so the coil element y or m a scanning cycle, resulting in a pulse signal output width for a scanning cycle.
The operation of this directive elements for the output relay y m and auxiliary relays, but no special relays.
PLS order used is shown in Figure 2.
2 PLF instructions
PLF pulse instruction directive, also known as falling edge. Its function is when a falling edge of the input pulse signal is detected, so the coil element y or m a scanning cycle, resulting in a pulse signal output width for a scanning cycle.
The operation of this directive elements for the output relay y m and auxiliary relays, but no special relays.

PLC set and reset commands usage

1 SET instructions
SET command called reset instructions. Its function is to: driving coil, making it with locking function, maintain the on State. In Figure 1, when the movable contact X0 closed, SET instruction is executed, Y0 coil connected. After first X0, Y0 coils to keep the on State to Y0 coil power, you must use the RST reset instructions.
Reset instructions operating elements for the output relay y s m, auxiliary relays and relay.
2 RST directive
RST command called reset instructions. Its function is to reset the coils. In Figure 1, when the movable contact X1 closed, RST instruction is executed, Y0 reset coils. After first X1, Y0 coils remain a disconnected state.
Reset instructions operating elements for the output relays, auxiliary relays y m t, s, integrating state relay timer, counter, c. It is also zero out the word element d, v, z.

PLC no operation (NOP), program end (END) command

1. no operation (NOP)
NOP: no operation

NOP instruction is typically used for the following aspects: Specifies a certain sequence content is empty, blank for use; some short circuit the contacts or circuit, as shown in Figure 7.24 (a), (b) shown cut off some of the circuit, as shown in Figure 7.24 (c), (d) shown in transform previous circuit, as shown in Figure 7.24 (e) as shown.
2. the procedure ends (END) command
END: end of instructions of a program

Link between touch screen and PLC

You what kind of touch screen and PLC, because each brand of touch screen and PLC connector wiring and communication methods are not the same, you get their wiring diagrams and PLC downloading programs, touchscreen computers configured, when creating a new project, will let you choose what to connect plc, what type, and then select Configure. Last connection plc and touch screen on the phone.

How the PLC ladder program execution

PLC is always in order from top to bottom in order to scan the user program (ladder diagram).  

When scanning a ladder diagram, always scan the ladder by the contact form on the left of the control circuit, after the first left and then right, and according to the sequence made up of contact points under control circuit logic operations

PLC selection guide

First, input/output (I/O) point estimate

I/O points should be considered when estimating the appropriate margins, usually according to the statistics of the input and output points, adding 10%~20% and Extensible

After allowance, as input and output point estimates. Actual orders, according to manufacturer product features of the PLC, the input and output points are rounded.

Second, the storage capacity estimation

Memory capacity is a programmable logic controller itself can provide hardware storage unit size, program capacity is user applications use memory cells in the memory size of the program capacity is less than the memory capacity. Design phase, because the user application has not prepared, therefore, program capacity is unknown at design time, in the program only after know. Design and selection in order to be able to program capacities have certain estimates, estimation of storage capacity is usually used instead.

Estimation of storage capacity memory has no fixed formula, many different formulae are given in the literature, in general are 10~15 times its digital I/O, plus 100 times times its analog I/O, memorythis number is the total number of words (16-bit word), and then press the 25% taking into account the number of allowances.

Three, the selection of control functions

The selection includes arithmetic, control function, communication function, functional programming, Diagnostics and selection of processing speed and other characteristics.

(A) functions

Simple PLC functions including operations, timing and counting functions; General PLC operation features include data transfer, arithmetic functions, such as; more complex arithmetic algebra, data transfer and other large PLC also have analog PID arithmetic and other advanced functions. With the advent of open systems, currently already has in the PLC communication function, some products have a communication with the slave, and some products have the same bit machine or PC communication, some products also have the factory or enterprise networks for data communications features. Selection from the actual application requirements, selecting the required functions. The majority of applications, just logic and timing function, some applications require data transfer and, when used for analog measurement and control, using algebra, numerical, and PID operation. To display data for decoding and encoding operations.

(B) control functions

Control functions including PID control arithmetic calculation, ratio control, feedforward compensation control operation should be determined according to the requirements. Main sequence logic control PLC, therefore, the most often used singleloop control of multiloop controller analogue or, sometimes using special smart input and output units to complete the necessary control functions, improve the processing speed and storage capacity savings of PLC. Such as PID control unit, high-speed counters, analog with speed compensation unit, ASC codeswitching unit and so on.

(C) communication functions

Large and medium PLC systems should support a variety of fieldbus and standard communication protocols (such as TCP/IP), needs to be with the plant management network (TCP/IP) connection. Communication protocols shall conform to ISO/IEEE standards, should be an open communications network.

PLC communication interface of the system should include both serial and parallel communication interface (RS2232C/422A/423/485), RIO, such as communications, industrial Ethernet, commonly used DCS interface; large and medium PLC communication bus (including interface devices and cables) should be 1:1 redundant configuration, communication should be consistent with international standards, communication distance should meet the equipment requirements.

PLC system of communication network, higher rate should be greater than 1Mbps of network traffic, load is less than 60%. PLC system of communications network main form has following several form: 1) PC mainly station, more Taiwan with model PLC for from station, composition simple PLC network; 2) 1 Taiwan PLC mainly station, other with model PLC for from station, constitute master-slave type PLC network; 3) PLC network through specific network interface connection to large DCS in the as DCS of child network; 4) dedicated PLC network (the manufacturers of dedicated PLC communications network).

To reduce CPU communication tasks, according to the network‘s practical needs, should have different communication features (such as point-to-point, fieldbus and industrial Ethernet) communications processors.

(D) programming features

Off-line programming mode: PLC programmer and the public a CPU, programming in programming mode, the CPU only provides services for programmers, not to control the equipment. Upon completion of programming, the programmer switches to run mode, CPU to control the equipment cannot be programmed. Off-line programming system costs can be reduced, but not convenient for using, and debugging. Programming: CPU and programmer has its own CPU, the host CPU is responsible for control and data exchange with the programmer within one scan cycle, programming the program online or send data to the host, the next scanning period, received by the host under the new program. This way costs more, but system debugging and easy, often used in large and medium PLC.

Five kinds of standardizing programming language: sequential function chart (SFC), ladder diagram (LD), function block diagram (FBD) three kinds of graphic language and statement form (IL), structured text (ST) in both languages. Select the programming language should follow the standard (IEC6113123), and also supports a variety of programming languages, such as C,Basic, to meet the control requirements for special applications.

(E) the diagnostic functions

PLC Diagnostics, including hardware and Software Diagnostics. Hardware diagnostic hardware logic to determine fault location hardware, Software Diagnostics diagnosis and diagnosis. Through software PLC diagnosis is within the internal performance and functionality, software for PLC CPU with external input/output components such as information exchange functions of diagnostics are diagnostic.

The strength of the PLC Diagnostics, directly affecting the technical requirements for operations and maintenance personnel, and mean time to repair.

(Vi) processing speed

PLC scanning mode. From the real-time view, processing speed, the sooner the better, if the signal duration is less than the scan time, the PLC will not scan the signals, causing loss of signal data.

Speed of processing and the user program length, CPU processing speed, software quality, and so on. At present, fast response, high speed PLC contact, about 0.2~0.4Ls per binary instruction execution time, so they can control requirements, will require the fastest-growing application needs. Scan cycle (scan processor cycles) should meet: scan time is less than 0.5ms/K for small PLC; large and medium PLC scan time is less than 0.2ms/K.

Four, the choice of models

(A) PLC type

PLC overall type and module type structure is divided into two categories, according to the application environment is divided into two types of installation and control installation; according to the CPU word size is divided into 1-bit, 4-bit, 8-bit, 16-bit, 32-bit, 64-bit, etc. From the application point of view, usually according to control feature selection or input/output points.

Overall PLC I/O points fixed, so user a choice small, small control systems; modular PLC offers a variety of I/O card or cards, so users can be more rational selection and configuration control system I/O points, feature extension is convenient and flexible, generally used for large and medium control systems.

(B) the choice of input/output modules

Input/output module options should be considered and its application requires unity. Input module for example, consider the signal level, signal transmission distance, signal isolators, signal power supply applications. The output module, should be given to selection of type of output modules, relay output modules with low prices, usually using voltage range, longer life expectancy, response time, etc; TRIAC output module applies to switch frequently, low power factor inductive loads, but is more expensive, less able to overload. Output module with DC output, communication output, and analog output, and so on, should be consistent with the application requirements.

Depending on the application requirements, selection of intelligent input/output modules, in order to improve control and reduce costs.

Considering the need for expanding the rack or remote I/O racks and so on.

(C) the power of choice

PLC power supply, in addition to the introduction of devices at the same time as the introduction of PLC according to the product specification design and the outer, PLC power supply should be designed to use 220VAC power supply, consistent with the domestic network voltage. Important applications should use an uninterruptible power supply or voltage regulator power supply.

If the PLC with its own power supply can be used, you should check for current meets the application requirements, you should design an external power supply. To prevent external high-voltage power supply by mistake and the introduction of PLC, isolation of the input and output signals are necessary, sometimes it can be a simple diode and fuse tube isolation.

(D) the storage choices

Due to the development of computer chips, memory prices have fallen, so, in order to ensure the normal operation of the project, the General requirements of PLC memory, 256 I/O points at least 8K memory options. When you need complex control functions, should choose the larger capacity, higher grade storage.

(E) the redundancy options

1. The redundancy control unit

(1) one of the most important: CPU (including memory) and the power supply should 1B1 redundancy.

(2) when needed can also select the PLC hardware and spare software hot standby redundant systems, 2 or 3 of redundant and fault-tolerant systems.

2. I/O interface unit redundancy

(1) control circuit the multi I/O card should be redundant.

(2) is an important point of multi I/O card can be redundant. 3) important I/O signals as needed, you can choose 2 or 3 of the I/O interface unit.

(Vi) economic considerations

When you select the PLC, should consider the priceperformance ratio. When considering the economy, should be applied taking into consideration scalability, operation, input-output ratio and other factors, compare and balance end up satisfied products.

ANB parallel circuit connected between PLC

ANB (circuit) parallel circuits connected in series between the block directive
(1) front circuit in series with the parallel circuit blocks and ANB instructions. Parallel circuit block starting with the LD or LDI instruction.
(2) If multiple parallel circuit blocks in sequence with ANB instructions front circuits connected in series, with no limit to the number of the ANB.
(3) the ANB directives can be used continuously, but like ORB directive limited to use below the 8.

PLC-contact instructions (FNC224~FNC246)

Contact compare total 18
(1) the LD contacts compare this kind of instruction mnemonics, code, and functionality.
(2) compare AND contact the class instruction mnemonic, code
(3) OR contact instructions
OR= instructions for use as shown in Figure 3-93, when X1 is ON, or the current value of the counter is 200, driving Y0.
Contact compare any data format of the source operand. 16-bit arithmetic step 5 program, 32-bit arithmetic 9 programs.