FOXBORO FBM211 P0914TN interface module

Description

FBM211 has a compact design, with a rugged extruded aluminum exterior for physical protection of the circuits. Enclosures specially designed for mounting the FBMs provide various levels of environmental protection, up to harsh environments, per ISA Standard S71.04.

The CPU consists of an arithmetic unit, a controller, a register, and a data, control, and status bus that establishes their correlation. The CPU unit also includes peripheral chips, bus interfaces, and related circuits. Memory is crucial for storing programs and data, and is an essential component module of PLC.

From the user’s perspective, there is no need to delve into the internal structure and circuit of the CPU, but there is still a need for sufficient understanding of the working mechanisms of each component. The controller of the CPU controls its operation, allowing it to read, express, and execute instructions. But the work rhythm is regulated by oscillation signals. An arithmetic unit is used for performing numerical or logical operations and operates under the command of a controller. Registers participate in operations and store intermediate results, which also operate under the command of the controller.

CPU speed and memory space are key parameters of PLC, which determine the working rate, number of IO, and software capacity of PLC, thereby limiting the control scale.
As for the I/O module, the interface between the PLC and the electrical circuit is based on the input and output part (I/O). The I/O module integrates the I/O circuit of the PLC, with the input register indicating the status of the input signal and the output point indicating the status of the output latch. The input module converts electrical signals into digital signals and enters the PLC system, while the output module reverses. I/O is divided into modules such as switch input (DI), switch output (DO), analog input (AI), and analog output (AO).
The common I/O classifications are as follows:
Switching value: According to the overall voltage level, there are 220VAC, 110VAC, and 24VDC. According to the isolation method, there are relay isolation and transistor isolation.

Analog quantity: Classified by signal type, there are current type (4-20mA, 0-20mA), voltage type (0-10V, 0-5V, -10-10V), etc. Classified by accuracy, there are 12bit, 14bit, 16bit, etc.

In addition to the commonly used IO mentioned above, there are also special IO modules, such as thermal resistors, thermocouples, pulse modules, etc.

Determine the module specifications and number based on the number of I/O points. I/O modules can be many or few, but their maximum number is limited by the basic configuration capabilities that the CPU can manage, that is, by the maximum number of backplane or rack slots.

Let’s take a look at the power module. The PLC power supply is used as an integrated circuit for the various modules of the PLC to provide working power. At the same time, some also provide 24V working power supply for the input circuit. The types of power input include: AC power supply (220VAC or 110VAC), DC power supply (commonly used as 24VDC).

Then there is the backplane or rack. The majority of modular PLCs use a backplane or rack, which is used to electrically establish connections between various modules, allowing the CPU to access all modules on the backplane. Mechanically, it maintains connections between each module, making each module form a whole.