1. Introduction
Schneider s TWIDO series of small PLC and text display (TSX08H04M), with easy to use, reliable performance, characterized by relatively low prices. The built-in Modbus communication protocol particularly suitable for the present a pump electronic control system industry (including submersible pumps, sewage pumps, centrifugal pumps, etc.). Because of its involvement, can fully upgrade a pump control system industry, the basic premise of not increasing production costs, the implementation of the system of communication.
2. System Overview
in a pump industry is currently widely used ABB 400 series drives, in addition to TWIDO than other brand PLC can not easily communicate with (without any additional conversion card case), To modify the inverter parameters, must be carried out directly on the converter operation, and general users to a certain lack of basic knowledge of converter, resulting in some of constant pressure water supply system, pump plant control system is doing, in order to enable users in the application process easy to operate, Fuji added a table PWX5 (from the thermostat from restructuring) to be upper and lower pressure settings, PID settings, and the role of other settings. As the Fuji PID table is more suitable temperature control system, the results of the effect of the whole system less than satisfactory. The inverter in the excellent performance of PID has not been used, the system of communication conditions in the absence of hard real-time monitoring.
use TWIDO PLC and the corresponding text display TSX08H04M can be easy for some brand of inverter, soft starter for real-time communications (such as: Schneider ATV31, ATV71, ATV68, ATS46 Series, ABB Company ACS400, 600 series), the user need only operate on the HMI can easily all parameters of the converter (which can read and write parameters) to modify and display (not to direct operation of inverter, soft starter) such as: motor parameter settings, pressure measuring range, for a given pressure setting, the internal PID value converter, converter start and stop the slope, fault alarm, multiple pump switch time setting, the pressure feedback value is displayed, the motor running parameters show and bar graph trends show more.
the system with the traditional constant pressure water supply system, the biggest difference is the control of the water pressure is the pressure in the pipeline and more frequency converter after the amendments made to the water pump running. Comparison of the traditional system only pressure or frequency of a parameter. These functions can be achieved for a pump industry is a comprehensive control system upgrade from the original independent unit (inverter, PLC no communication links) to upgrade to a communication control system. In today s competitive market, the introduction of a new and excellent performance with competitive products (not in the basic premise of increased production costs) must be able to win more market share.
3. PLC and inverter communication
TWIDO PLC and text display TSX08H04M and Schneider Inverter ATV31, ABB ACS400 frequency converter company communication principle description:
(1) ATV31 Inverter: (details please refer to "TWIDO PLC and Inverter ATV31 Communication Guide" document)
HMI ------ text display (4 line display or 2 line display)
PLC ------ Dual communication port programmable controller (TWDLCAA40DRF)
Schneider Inverter ATV31 ---
Constant pressure water supply system works as shown:
(2) ACS 400 inverter
ACS400 through the standard Modbus bus and Twido PLC to communicate. ACS400 control signal can come from the Modbus serial communications, but also some from the communication, the other from the other control channel, such as AI / DI terminal or control panel.
According to a pump industry, the different needs of our constant pressure water supply is delayed 2 to illustrate the ACS400 and Twido PLC is how to communicate, and how to read and write parameters.
Requirements: ???? through text display HMI ACS400 can be configured some other numbers and observations (pressure setting, the motor parameters, PID parameters, run the process monitoring, etc.).
???? ACS400 pressure setting on the need to get through the RS485 communication port.
???? pressure feedback signal can be 0-10V or 4-20mA.
???? ACS400 frequency converter control method uses terminal control formula.
Step 1:
Reference ACS400 inverter user manual pages PID control wiring diagram P51 (pressure for a given value of AI1 not answer).
Step 2:
Twido PLC ACS400 expansion port and the connection diagram.
Note: The link distance: 200 meters (direct connection) or 1000 meters (plus repeaters) multi-point connection, up to the 18 inverters.
Step 3: Twido PLC communications port settings:
Programming Port: Protocol Type: Modbus , address 1, the communication rate 9600,1 stop bit, even parity, mode of communication RTU (note the specific parameter settings and text display line as long as you can).
Expansion port: protocol type: Modbus , address 1, the communication rate 9600,1 stop bit, even parity, mode of communication RTU (note the specific parameter setting can be as long as the same transducer).
Step 4: ACS400 communication parameter settings:
5005 STD Modbus
5006 STD Modbus
5201 1 (station number, if only one set converter, the default value)
5202 9600
5203 1 (even check)
Note: At this point, if the ACS400 and Twido PLC power, then Twido PLC on the com lights should be in communication state, indicating the normal communications between them.
Step 5: the ACS400 is set to PID Control macro. (9902 = 6)
PID control parameters refer to P51
of which 1103 is set to com, 1106 is set to com
purpose: to make EXT REF1 by the PLC through the RS485 port settings (pressure setting)
Step 6: HMI display screen text editor (slightly)
Twido PLC communication programming examples (the program with Twido PLC and ATV28 communications programming is basically the same procedure. The difference is that the wording of the address for the ACS400 a "minus one way." Or (ACS400 number of addresses minus 1) is Twido PLC the corresponding address.)
patients: pressure setting programming example:
???? ACS400 of the pressure setting address 0119 = > Twido PLC type "0118" address
4. Summary
currently living with the improvement of water quality have become increasingly demanding the abolition of high-rise buildings on the water tank has become the trend of secondary pollution, while the previous constant pressure water supply system operation more complex systems parameter adjustment must be carried out directly on the inverter operation, if there is no corresponding technical support, difficult for users to modify the system to be dependent on the manufacturer. When using the Schneider s text display HMI, dual communication port TWIDO PLC and the corresponding inverter, the system becomes a very easy to operate the system, whether to modify the parameters of the inverter or the pressure on the system reset just text display (all Chinese use the single) can operate on.
the realization of the system depends on the Schneider Small PLC TWIDO have very good communication. Combined with its relatively modest price makes the sales industry in a pump, constant pressure water supply system can be rapidly developed and applied.