1200 Siemens high speed counter how to measure the forward and reverse rotation of the motor

You can refer to this. There is a phase difference in the AB phase, which is used to determine whether the encoder is forward or reversed by whether A is ahead of B or lag. This is Mitsubishi's, the principle is the same, you just change it to Siemens.

I. Introduction. In motion control, it is often necessary to count pulses, such as rotary encoders to measure the speed of motors or simplified proximity switch signals. For example, in the low-end PLCs of Siemens, the S7-200 or S7-1200 series PLCs provide integrated high-speed counters and corresponding configurations and instructions.

Second, the implementation of high-speed counting.

Generally, when the switching frequency is greater than 50Hz, it is difficult to meet the needs of counting by using the ordinary digital input point DI. Below 50Hz depends on the scanning time of the CPU, which depends on many factors, such as the complexity of the program, etc. When the switching frequency is greater than 50Hz, a high-speed PLC counter is recommended.

Interrupt processing. We take the current mainstream S7-1200 PLC as an example, and introduce the method of implementing the PLC high-speed counter in its programming and debugging software Portal V13. One of them is to adopt hardware interrupt, first add the program block hardware interrupt tissue block ob40, as shown in Figure 1.

A hardware interrupt is when the PLC CPU responds to a signal change from the PLC hard junction independently of the scan cycle. We can configure which DI points and which ways to respond to hardware interrupts.

The PLC CPU cycles through the program and flushes the input and output image registers, while hardware interrupts can respond quickly to changes in input and output regardless of program scanning. As shown in Figure 2, in the hardware configuration CPU property page, we can configure the hardware interrupt mode of the digital input point (i.e., the channel): whether edge detection is enabled, and hardware interrupt and priority.

Once configured, write the counting program in the corresponding interrupt tissue block ob40.

Integrated high-speed counting channel.

We can use the digital input points that come with the PLC CPU (for example, configured as a high-speed counter, in fact, it is difficult to strictly distinguish between the first method "interrupt handling" and the second method "integrated high-speed counting channel", the second method is essentially the first method.

Different models of CPUs can be configured with different high-speed counting channels, as well as different modes. Taking CPU1212C as an example, the six vertices can be configured as high-speed counters, corresponding to HSC1 and HSC6, as shown in Figure 3 in the hardware configuration CPU property page, configure whether HSC1 is enabled, and whether the counting type, working mode, and counting direction are configured. For detailed explanations, press F1 or find information online for help.

The high-speed pulse counter must have a counting time, such as the counting time is 1 second, if the number of pulses per revolution is one, that is, one revolution outputs a pulse, then, the data of the one-second meter multiplied by 60 is the number of revolutions. Because the number of revolutions is calculated in terms of how many revolutions per minute. If there are 60 pulses per revolution, then the number of revolutions measured by the high-speed pulse counter is the number of revolutions per second.

Divide the cumulative number obtained by the high-speed counter by the number of single turns of the encoder, or read the cumulative number of the encoder's z-channels directly.

No, this or the single finger can be used without adding hardware to guess the pulse spike group Jingchong detection. Because the servo control can be controlled a lot by network communication, if you add a positioning module, you can control more.

1. It can be tested with mode 10, so that it will automatically reset after one rotation.

2. There will always be errors in the values.

This is not very difficult to implement, but it is difficult to say clearly, the main steps: 1. Install the hardware correctly and wiring it.

2. Write PLC programs.

a. Write counter allow and interrupt allow commands.

b. The counted value obtained by processing can be processed as the positioning value, or it can be processed as the frequency, etc., and the output of the inverter can be controlled according to the counting value.

Measure motor speed using PLC and encoder:

A rotary encoder is installed on the shaft of the motor or hydraulic motor, and the A-phase pulse, B-phase pulse, and reset Z signals of the rotary encoder are respectively connected to the three high-speed counting inputs of the programmable controller (PLC), so that the speed of the motor is measured by PLC and encoder.

You use a speed counter to connect the motor, and then send the collected pulse signal to the PLC analog terminal, which is internally converted into a digital signal, and then transmitted to the configuration digital display part of the computer to display the speed correctly.

First of all, you need two pulsemeter channels to connect to two encoders. There is no need for AB phase access, only single-phase access is required. And get the running frequency of the motor through the frequency counting command.

After getting the frequency, the best way is to use the PID command and the PLC to control the analog quantity through the PID output to get the actual value of the motor speed.

General speed sampling are selected rotary encoder, the number of pulses of the encoder can be selected more, as much as possible, but he will be limited by the speed of the motor and PLC, I use Mitsubishi PLC as an example X0, X1, X3 can be directly connected to the encoder output, they are also high-speed counting input, PLC high-speed counter 100 milliseconds sampling once, so that you can fold to the motor speed, note that the rotary encoder must be coaxial connection with the motor, if connected with a pulley to consider their transmission ratio.

Figure out how many pulses are needed for a turn, just use interrupts and don't lose a step.

The effect is very limited, it cannot be used as a servo motor, but because it is still useful in ordinary occasions, in fact, the inverter is already dealing with this kind of thing.

Compare it directly! If the satisfaction count is greater than the preset value, it will be slowed down.