Learning PLC

1) CPU in STOP mode, the status bar displays a red background STOP. Switch the CPU to RUN mode , the status bar turns green background RUN , it can be monitored . 2 ) not using the CALL instruction block is monitored , block call condition to be monitored is not satisfied , the block being monitored is not executed , you can not monitor it . 3 ) operating system only monitors the selected block and the block after it . Block does not monitor the selected program before .

Also known as floating-point real number (Real), in STEP 7, expressed as a decimal floating-point number. I read some people say for S7-300 / 400 "ROUND instruction is actually round 6 into 5, if you really want to shed 5 into 4, you can add pre-0.1."      To be honest I have not noticed this last instruction details. To this end first consult the online help instructions:      "ROUND (rounded to a long integer) IN parameter content to read floating-point number and converts it to a double integer (32-bit) result to the nearest integer (rounded to the nearest value). If the float interposed between two integers, the even number is returned. the results output by the parameter OUT. "      We called "rounding to nearest" to rounding. Here are the results of simulation experiment, rounding it seems, there is no 5 round 6 into the problem.      2.49999 input, output 2       2.50001 input, output 3       Float just returned even between two integers,

ctrl + L downloads    ctrl + d module information    ctrl + i mode    ctrl + alt + R reference data    alt + entre object properties    F2 normally open contact    F3 normally closed contact    F7 coil    ctrl + R inserted block    alt + F9 to insert an empty box down    ctrl + 1 LAD Ladder    ctrl + 2 STL Statement List    ctrl + 3 FBD Function Block Diagram    ctrl + Q symbolic expressions    ctrl + shift + Q sign information    ctrl + alt + T symbol table    ctrl alt + E Custom , you can change the color and the like,    ctrl + 7 Monitoring    ctrl + alt + T variable table

OPN DB100 L 0 LAR1 L 3500 ITD RLD 3 + AR1 L DBW [AR1, P # 0.0] // reads the DB100.DBW3500 But when the address is > 4095 , due to the value of 3 after the RLD 4096 has been greater than or equal 32768 AR1 caused the wrong value ( great value ) . So in this case has left three address value can not be obtained correctly . Here is my Replies : The program can be simplified as in the figure below procedure : L # 4500 is a two- word constant , so there is no limit of 4095 .     Address pointer constant P # 4500.0 byte address is 4500 -bit byte address within the 0, P # 4500.0 corresponds to the product of 3500 and 8 ( in bits integer units ) . RLD 3 ( left 3 ) is equivalent to multiplying 8 .  

S7-200 CPU communication port can be set to Freeport mode. When you select Freeport mode, the user program can completely control the operation of the communication port, the communication protocol is completely controlled by the user program. Communications port on the S7-200 CPU are electrically standard RS-485 half-duplex serial communication port. The format of this serial character communication may include: A start bit Seven or eight characters (data bytes) An odd / even parity bit, or no parity bit One stop bit   Speed ​​communication baud rate can be set to 1200,2400,4800,9600,19200,38400,57600 or 112500.   . Micro / WIN instruction library two (USS and Modbus RTU) is programmed using the free port mode implemented. Also note that: Communication during debugging, you can use the PC / PPI cable (provided to the free port communication mode) to connect the PC and CPU, running on a PC serial debugging software (for Windows or Hyper Terminal- HyperTerminal) debugging Freepor

1, the overcurrent (OC) Inverter over-current alarm is the most frequent phenomenon. 1.1 phenomenon      (1) restarts, a liter of speed on the trip. This is very serious over-current phenomenon. Main reasons: the load short circuit, mechanical parts are stuck; inverter module damage; motor torque is too small to cause such phenomena.      (2) on the power on the jump, a phenomenon generally can not be reset, for two main reasons: module bad, bad driver circuit, the current detection circuit bad.      (3) does not restart immediately when the trip but when accelerating, for two main reasons: the acceleration time is set too short, the current limit is set too small, the torque compensation (V / F) set higher.   2, overvoltage (OU)      Overvoltage alarm usually occurs during idle time, mainly due to the deceleration time is too short or braking resistor and braking unit in question.       3, under voltage (Uu)      Brown is also a problem in that we use frequently

Common drive in use, whether it can meet the requirements of the transmission system, the drive parameter setting is very important, if parameters are set incorrectly, can cause the drive does not work.    parameter settings        Common drive, when general factory, manufacturers of each parameter has a default value, these parameters are called factory values. In the case of values ​​of these parameters, the user can run the normal mode of operation the panel, but the panel does not meet the operating requirements of the majority of the transmission system. Therefore, users in the correct use of the drive, when you want to drive parameters from the following aspects:      (1) Check the motor parameters, set the drive power, current, voltage, speed, maximum frequency of the motor in the parameters, these parameters can be obtained directly from the motor nameplate.      (2) the drive to take control, which speed control, torque control, PID control or other means. After

Function instruction format   Function instruction by number FNC00 ~ FNC294 representation, and gives the corresponding mnemonic (mostly represented by the English name or abbreviation). For example FNC45 mnemonic is MEAN (average), type FNC45 if using simple programmer, can also type mnemonic MEAN If smart programmer or programming on your computer. Some functional commands no operands, while most of the function instruction has operands 1-4. As shown in FIG. 1 is a command to calculate the average, it has three operands, [S] represents the source operand, [D] represents the destination operand, if the index function can be expressed as [S ·] and [ D ·]. When more than one source or target when using [S1 ·], [S2 ·], [D1 ·], [D2 ·] represents. It represents the other operand by n and m, which are often used to represent the constant K and H, or as a source and destination operand supplement, when such a long time is available operands n1, n2 and m1, m2, etc. to represent.

1. No operation instruction NOP (0 0) 2. End instruction END (01) 3 . Interlocked instruction IL (02) and interlock clear instructions ILC (0 3)   4 . Jump start instruction JMP (0 4) and JUMP END instruction JME (0 5) 5 . By- bit shift instructions SFT (10) 6 . Latch command KEEP (11) 7 . Frontier differential pulse command DIFU (13) and a trailing edge differential pulse command DIFD (14)   . 8. Quick Timer instruction TIMH (15) 9. Channel shift instruction WSFT (16) 10 . Reversible counter instruction CNTR (12) 11 . Compare instruction CMP (20) 12 . Data transfer instruction MOV (21) and inverted data transfer instruction MOVN (22) 13 . Carry bit instruction STC (40) and the carry reset bit instruction CLC (41) 14 . Add instruction ADD (30) This Directive is the content of the contents of the two channels or one channel and a 15 . Subtract instruction SUB (31)

S7-200 interface modules are mainly digital I / O modules, analog I / O and communication modules .  ( A ) digital I / O modules Digital I / O module is designed to solve the native integrated digital input / output points can not be used to meet the needs of expansion modules . S7-200PLC currently provide a total of three categories , a total of nine kinds of digital I / O modules. 1. EM221 digital input expansion module 8DI, DC24V ( DC )   2. EM222 digital output expansion module 8DO, DC24V ( DC output ) 8DO, Relay (DC24V / AC24 ~ 230V) ( relay output) 3. EM223 digital mixing module 4DI (DC24V), 4DO (DC24V / 2A) 4DI (DC24V), 4DO (Relay 2A) 8DI (DC24V), 8DO (DC24V / 2A) 8DI (DC24V), 8DO (Relay 2A) 16DI (DC24V), 16DO (Relay 2A) 16DI (DC24V), 16DO (DC24V / 2A)   (B) the analog I / O modules Analog I / O modules provide analog input and analog output extensions. S7-200 analog expansion module has a greater adaptability, it can be directly connected