FAQ 2 of Hollysys PLC

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Hollysys PLC FAQ 2

1 What analog processing modules does G3 series PLC have

answer: with the improvement of the performance of Small PLC and the expansion of its application scope, small PLC is no longer limited to the traditional discrete control occasions, and began to be more and more used in process control. Similarly, for Small PLC, analog signal processing is becoming more and more important, which is 39 yuan lower than that at the beginning of the year

g3 series PLC has several analog processing modules. Including analog input modules lm3310, lm3310a, lm3310b, lm3313, analog output module lm3320, analog input and output module lm3330, etc

lm3310, lm3310a and lm3310b are 4-channel standard signal input modules, and the signals that can be input are 0~10v/4~20ma/0~20ma. Lm3313 is an 8-channel analog input, and the input signal includes -10~10v/-20~20ma. Lm3320 is a 2-channel analog output module, and the signals that can be output include 0~10v/0~20ma. Lm3330 is a 4-channel analog input/1-channel analog output module. Its input signal is similar to lm3310a, and its output signal is similar to lm3320

g3 series PLC also has several special temperature acquisition modules, which can be directly connected to the temperature sensor without adding a transmitter. Lm3311 is a 4-channel thermocouple temperature acquisition module, which allows access to standard thermocouple sensors. Lm3312 is a 4-channel thermistor temperature acquisition module, which allows access to standard thermistors such as PT100 or cu50. Lm3314 is an 8-channel thermistor temperature acquisition module, which allows access to thermistors with negative temperature coefficient and optional b value

3310, lm3310a, lm3310b what are the differences between these three modules

answer: lm3310, lm3310a and lm3310b are 4-channel standard signal input modules, but there are some differences between the three. The lm3310 input is differential and uses a 12 bit a/d conversion chip, which is suitable for occasions requiring fast input response. The lm3310a input terminal is a single ended form, which also uses a 12 bit a/d conversion chip, which is suitable for occasions requiring fast input response. But affecting the normal use of the experimental machine, lm3310b adopts a single ended input, 16 bit a/d conversion chip, which is suitable for occasions requiring high precision, but not requiring fast response

at the same time, it should be noted that since lm3310a and lm3310b are single ended inputs, if the negative ends of multiple transmitters cannot be shorted, only one transmitter can be connected at most, or lm3310 module can be selected

3. Lm3320 module is used for analog output, but if you only want to output 0 ~ 5V, can it be achieved

answer: Yes. Lm3320 can realize 0 ~ 20mA or 0 ~ 10V output. If you only want to output 0 ~ 5V, it can be achieved

4. The standard signal sent by the load cell through the transmitter can be voltage or current signal. Is there any requirement for lm3310? How is the value of this signal reflected in the PLC register

answer: lm3310 can receive four signals: voltage (0 ~ 10V), current (0 ~ 20mA) or current (4 ~ 20mA). And each signal can be different, just configure the corresponding signal during PLC configuration. The corresponding relationship is as follows:

for example, your 0-1000 kg corresponds to 0-10V, while 0-10V in PLC corresponds to 0 ~ 65535, so your 0-1000 kg corresponds to 0 ~ 65535 in PLC

5. Can the thermocouple or thermal resistance signal be directly connected to g3plc

answer: of course, the analog expansion module of G3 series PLC includes not only standard signal input module, but also special temperature module expansion module: thermistor module, thermocouple module, thermistor module, and the analog accuracy is high. Thermocouple support types include J, K, t, N, e, R, s, B, -80~80mv, and thermal resistance support types include cu50 and PT100

6. What effect does analog filtering have? How to set

answer: generally, if G3's analog filtering function is selected, there is no need to prepare the user's filtering program separately. If analog filtering is selected for a channel, the CPU will automatically read the analog input value before each program scanning cycle. This value is the filtered value and the average value of the set number of samples. The parameter settings of analog quantity (sampling number and dead band value) are valid for all analog quantity signal input channels. If a channel is not filtered, the CPU will not read the average filter value at the beginning of the program scanning cycle, but directly read the actual value at that time only when the user program accesses this analog channel

in powerpro software, you can filter and set the analog input signal directly. Take lm3310 as an example, its setting parameters and actual filtering time are shown in the table below

7. What should we pay attention to when setting analog filtering

answer: pay attention to the following points:

1) selecting filters for analog inputs that change slowly can suppress fluctuations

2) choosing a smaller number of samples and dead band values for analog inputs that change faster will speed up the response. What will the aircraft look like after disassembly? Speed

3) do not use filters for analog values that change rapidly

8. How to set the dead band value of G3 analog filtering

answer: dead band value refers to the dead band value set by the user, and the range of values is. When starting the filtering function, when the difference between the current acquisition result of analog quantity and the value after the last filtering exceeds the set dead band value, the acquisition module directly outputs the current acquisition result; Otherwise, the filtered conversion result will be output. A deadband value of 0 disables the deadband parameter

9. What is the accuracy of G3 analog input signal

answer: the pseudo input module has two parameters that are easy to confuse:

1) the resolution of analog conversion

2) the accuracy (error) of analog conversion

the resolution is the conversion accuracy of a/d analog conversion chip, that is, how many bits are used to express the analog quantity. For G3 analog module, lm3310b has a resolution of 16, which fundamentally avoids the influence of zero drift and temperature drift of traditional analog sensor on measurement results. The conversion resolution of other modules is 12 bits

the accuracy of analog conversion depends not only on the resolution of a/d conversion, but also on the peripheral circuit of the conversion chip. In practical application, the input analog signal will have fluctuations, noise and interference, and the internal analog circuit will also produce noise

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