Omron PLC technical problems and solutions - Database & Sql Blog Articles

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1. What does the normally broken sign mean? Under what circumstances can the normally-off flag be used, and when is the normally-off flag turned on?
1.P_OFF ​​bit (normally open) under no circumstances will be conductors, generally used to deal with situations where ON is not allowed. For example, CNT instruction, if the customer does not allow resetting in any case, then it is normally open on the RESET side. P_OFF
2. In addition, the actual normally closed P_OFF ​​is equal to the normally open P_ON
Second, can the PID calculation of CP1H control the forward and reverse of the same motor (switching quantity control), or can it be realized by other instructions?
The output after PID operation is a continuous quantity. Even if it is the PID control of the digital output, the output is also the duty cycle. Therefore, it is impossible to directly realize the forward and reverse. You need to use the comparison function to achieve the positive and negative reversal. For example, When the output of 芇ID is greater than 50%, let the motor forward, and vice versa. I think it is to receive the 4-20mA signal with the PID command, but because the PID needs to set the target value, I only need to set one. Target range, 4-20mA should set the target range, PID command will output the operation result to the corresponding relay, but I don't know how the output of the PID instruction changes, so I feel a headache; I read about the PTO command, but it It can only be output to one relay, and I need several relays to receive the pulse signal at the same time.
You can turn this target range into a point and give it a set value. The PID output is of course given according to the proportional integral differential operation. It is an automatic control, so there is no fixed value. If you need a fixed input corresponding to a fixed input, you can use the calibration directly. It is not necessary. PID. The TPO command gives an output, and an output can be connected to multiple relays as long as the power is sufficient, but the problem is that you are talking about multiple relays controlled by the same signal, how can some of them be high and some are low, their level It must be consistent. If you want to be inconsistent, use other plc output point strings to control them separately in the respective loops, but the key is when you need which relay to turn ON, and when you need which relay to turn OFF. This logic must be clear and written into the PLC program beforehand. .
4. Can the output of the PID operation be positive and negative? What instructions can I use?
A PID instruction can only be forward rotation control or reverse rotation control. It cannot be reversed and controlled at the same time. For example, you can use two PID instructions. 5. This control method is used in industrial heat treatment furnaces. The main working principle is : Input 4-20 mA signal, 4-11 mA is one processing interval (cooling action), 11-13 mA is dead zone (no action required), 13-20 mA is another processing zone (heating action). When in the heating range, 13-20mA corresponds to 0-100% output, but this 0-100% output needs to be converted to a pulse output of 10s period, assuming 4 relay output points are required, with the size of the input signal, 4 relays It needs different ways to work. When the signal is large, all four work. When the signal is relatively small, each relay is required to be intermittently rotated. For the cooling interval, the input signal is inversely proportional to the output. I don't know how to use CP1H to program. Thank you for the 4 signals when the signal is large. The signal is intermittently rotated every time. When is the signal large, when is the signal small? How much time is the interval rotation work rotated? How is the inverse ratio of the cooling interval specific? The heating is proportional, and the cooling is inversely proportional. That is to say, there is no need to use PID control? Is it necessary to use other control devices when cooling, the output needs to be converted into pulses? Sixth, decimal and floating point stored in OMRON PLC how the decimals are stored in the DM area, such as the 10.625 into the DM area, How it is stored, how the decimal is converted to binary.
2 Is floating point and decimal a concept?
3 If I use a decimal to perform operations, do I have to use floating-point arithmetic instructions, or convert decimals to floating-point numbers? How do I convert them?
1. There are two consecutive channels in the format of floating point number, that is, a floating point number is represented by a 32-bit binary number. The two channels have a total of 32 bits (0-31), and the highest bit represents the symbol, 23-30. Bits represent the exponent and bits 0-22 are the mantissa.
2. The data used in the above format in OMRON's PLC is a floating point number, because floating point numbers contain fractional parts, so if you want to use more complicated and accurate decimal calculations, basically use floating point numbers.
3. Complex uses floating point numbers. If you only need one or two decimal places, you can consider enlarging the integer by 10 or 100 times. The result is also to retain the decimal, but the data itself is still hex or BCD. Only you know that the last one or two are decimals. The premise of this method is that the number of data calculations is sufficient.
7. There is a TXD instruction in the middle of the program. It is assumed that the data transmission time is 50ms. The PLC execution TXD instruction should be less than 50ms. Is it necessary to wait for the instruction after TXD to complete the TXD? That is to say after 50ms
The execution of TXD is the actual processing time of the peripheral service. In the program execution, the instruction execution time of TXD is 256 bytes, for example, CP1H is only 1.2ms.
After the execution is completed, the next instruction is executed immediately. At the end of the program execution of one scan cycle, the data is sent after the peripheral service time is reached. This time is longer than the previous instruction execution time. The number of bytes depends on the number of bytes. It is several tens of ms. If the peripherals of one scan cycle cannot be sent, the peripheral service time of the next scan cycle continues to be transmitted. 8. The range of the analog quantity set in CP1H is 6000 and 12000. This is How is it determined?
2. In the PID calculation, if I make a PIDA instruction, I need to adjust it every time I start the PID, or after the first adjustment (after modifying the adjusted parameters and writing it into the original PID), afterwards Don't adjust it when starting up, the future action is the same.
1.6000 and 12000 are resolutions, that is, dividing an input signal such as 4-20ma into 6000 copies or 12000 copies. The specific setting is to select 6000 or 12000 at the top of the built-in ADDA column in the software settings, and then download it and power off it.
2. If the system does not change frequently, it does not need to be set every time. It is OK to start the PID control directly. 9. The pulse setting is set with 4 bits of 8421 code. The output is PLS2, and the PLC reads 16 in. System,
How to convert to decimal, that is, if the setting is 1234 pulses, the PLS2 output is also
1234 pulses instead of 4660 pulses.
PLS2 pulse output command, the set number of pulses, acceleration and deceleration rate, target frequency, etc. are all hexadecimal.
Is the hexadecimal number read by the PLC as the number of pulses set by the PLS2 command?
If the input "1234" is a hexadecimal number, directly use the hexadecimal number as PLS2.