Foxboro P0914XA – Slot Rack Module

Description

In PLC, there are no more than three quantities: switching quantity, analog quantity, and pulse quantity. By understanding the relationship between the three, you can become proficient in PLC.

1. Switching quantity, also known as logical quantity, refers to having only two values, 0 or 1, ON or OFF. It is the most commonly used control, and controlling it is an advantage of PLC and also the most basic application of PLC.

The purpose of on-off control is to generate corresponding on-off outputs from the PLC based on the current input combination of on-off values and the historical input sequence, so that the system can work in a certain order. So, sometimes also known as sequential control.
And sequential control can be divided into manual, semi-automatic, or automatic. The control principles adopted include decentralized, centralized, and hybrid control.

2. Analog quantity refers to some continuously changing physical quantities, such as voltage, current, pressure, speed, flow rate, etc.
PLC was developed after the introduction of microprocessing technology through relay control, and can be conveniently and reliably used for on-off control. Due to the fact that analog quantities can be converted into digital quantities, which are only multi bit switching quantities, the converted analog quantities can also be reliably processed and controlled by the PLC.

Due to the frequent occurrence of analog quantities in continuous production processes, analog quantity control is sometimes referred to as process control.

Analog quantities are mostly non electrical quantities, while PLC can only handle digital quantities and electrical quantities. All conversions between them require sensors to convert analog quantities into digital quantities. If this electric quantity is not standard, it needs to go through a transmitter to convert the non-standard electric quantity into standard electrical signals, such as 4-20mA, 1-5V, 0-10V, and so on.
At the same time, there must be an analog input unit (A/D) to convert these standard electrical signals into digital signals; Analog output unit (D/A) to convert digital signals processed by PLC into analog signals – standard electrical signals.

So the conversion between standard electrical signals and digital quantities requires various operations. This requires a clear understanding of the resolution of the analog unit and the standard electrical signal. For example:

The resolution of the PLC simulation unit is 1/32767, and the corresponding standard power is 0-10V. The temperature value to be detected is 0-100 ℃. So 0-32767 corresponds to a temperature value of 0-100 ℃. Then calculate that the numerical value corresponding to 1 ℃ is 327.67. If you want to precision the temperature value to 0.1 ℃, you can set it to 327.67/10.

Analog control includes: feedback control, feedforward control, proportional control, fuzzy control, etc. These are the calculation processes of internal digital quantities in PLC.

3. Pulse quantity is a digital quantity whose value always alternates between 0 (low level) and 1 (high level). The number of alternating pulses per second is called frequency.

The control purpose of PLC pulse quantity mainly includes position control, motion control, trajectory control, etc. For example, the application of pulse number in angle control. The subdivision of the stepper motor driver is 10000 per turn, requiring the stepper motor to rotate 90 degrees. So the pulse value to be acted on is 10000/(360/90)=2500.

Recommendation:
DS200TCTEG1A
DS200TCSAG1A
DS200TCRAG2A
DS200TCRAG1A
DS200TCQFG1A
DS200TCQFF1AAD
DS200TCQFF1AAA
DS200TCQEP2AAB
DS200TCQEP1ABB
DS200TCQEG2A
DS200TCQEG1A
DS200TCQCG1B
DS200TCQCG1A
DS200TCQBG2B
DS200TCQBG2A
DS200TCQBG1B
DS200TCQBG1A
DS200TCQBF2BAA
DS200TCQAG2B
DS200TCQAG1B
DS200TCQAG1A
DS200TCPSG1A
DS200TCPDG3BE
DS200TCPDG3B
DS200TCPDG2B
DS200TCPDG1B
DS200TCPDG1A
DS200TCPAG1A
DS200TCPAF2AAB
DS200TCPAF1AAC
DS200TCEAP1BBD
DS200TCEAP1BBC
DS200TCEAG2B