Introduction to the four commonly used closed-loop

2022-09-22
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The four commonly used closed-loop control modules of Siemens PLC

fm355 has four closed-loop control channels for pressure, flow, liquid level and other control, including optimized temperature control algorithm and PID algorithm. Fm355c is a continuous controller with 4 analog outputs and low accuracy in recent years. FM355S is a stepping or pulse controller with 8 digital output points. After CPU shutdown or failure, fm355 people can continue to run, and the control program is stored in the module

fm355 has four analog inputs for collecting analog values and feedforward control values, and an additional analog input for temperature compensation of thermocouples. Different sensors can be used, such as thermocouples, PT100 thermistors, voltage sensors, and current sensors. Fm355 has four separate closed-loop control channels, which can realize and will successively set up R & D/marketing centers in Shanghai, Germany and the United States. Customized control, cascade control, proportional control and 3-component control can be integrated into one system. There are automatic, manual, safe, follow-up and back operation modes. The sampling time is 20-100ms at 12 bit resolution and 100-500ms at 14 bit resolution

the self optimizing temperature control algorithm is stored in the meter fast. When the set point changes more than 12%, the liberalization is automatically started; The configuration software package can be used to optimize the PID control algorithm

if the CPU is faulty or the CPU stops running, the controller can continue to control on its own. For this reason, adjustable safety set points or safety adjustment variables are set in the "backup mode" function. All parameters of the fuzzy temperature controller can be read and modified, or other parameters can be modified

2. FM closed-loop control module

fm is a 4-channel closed-loop control module suitable for temperature closed-loop control, which can easily realize automatic temperature control, including heating and cooling control, as well as the combined control of heating and cooling. FMC is a continuous controller with 4 analog outputs, and FMS is a stepping or pulse controller with 8 digital outputs. FM can still operate after CPU shutdown or failure

3. Fm455 closed-loop control module

12 bit resolution makes the sampling time 20-180ms, 100-1700ms at 14 bits (related to the number of analog inputs actually used), with 16 digital inputs

4. Fmdp Application module

fmdp is designed for free attitude closed-loop control. It also includes library functions of 300 function blocks and CFC continuous function diagram graphical configuration software, with PROFIBUS-DP interface

the basic module of fmdp can perform calculation, open-loop and closed-loop control, and i/o and communication can be extended through the expansion module

exmi/o expansion module is an optional plug-in expansion module of fmdp, which is used to read and output signals with time requirements. There are digital/analog input/output modules, which can connect incremental and absolute encoders, and there are four 12 bit analog outputs

exm448 communication expansion module is an optional insertion expansion module of fmdp. PROFIBUS-DP or SIMOLINK can be used for high-speed communication, with a spare slot, which can be inserted into the Masterdrives optional mode for establishing SIMOLINK optical fiber communication

fmdp also has some accessory interface modules, including digital input, digital output and program storage modules

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