Overview As technology advances, the programmable logic controller (PLC)??????the automatic control system in many industries and fields have been widely used in food packaging machinery and ACR INDUSTRY is no exception. PLC and industrial human-machine interface (HMI) are largely used for packaging machines and water chillers, such as absorption chillers in the last, OMRON s C200HB1, CSl, CJl series PLC on its excellent performance (computing capabilities network communication functions, easy to use open communication protocols, etc.) received the endorsement of the business and users has been widely used. It s networking features allow enterprises to service centers in their own homes can monitor users worldwide unit used to run the full state and data to help customers solve problems they encounter in running, reminding customers to protect and maintain machines, and units to help customers regain control procedures and set the unit operating parameters and so on. This greatly improved the quality and efficiency of services, but also for saving a lot of expenses. However, due to cost reasons, these series of PLC can not be in the other cold water chiller units such as wind, water-cooled screw machine, piston machine and other products made application, for OMRON launched another model CPM2AH, this model small size, expansion capability, high cost performance, very suitable for food packaging machinery and cold water, and air-cooledUnit in use. The following example in order to control the chiller further explanation. A control system configuration CPM2AH Series PLC is a small chassis together with advanced features and superior performance products. The basic unit has four types 20,30,40,60 points, including a digital input and high-speed pulse input, relay output, according to the needs of system development, can increase the expansion module, expansion of the modules include switching Input Output Module , Pt100 temperature input module (TS101/TS102), current and voltage input module (AD041) and the analog output module (DA041). In the communication can be:
(1) through the Host link to connect to the computer system;
(2) by 1:1 Link with OMRON PLC to communicate with other series;
(3) by Compobus / S and Device Net remote expansion modules, enabling distributed control.
OMRON s PLC products as very versatile, many companies can and its touch screen communication connection, so can priceCells, functional and technical characteristics of the touch screen to select the appropriate products and supporting the use of PLC.
For other special requirements, or design need to increase the amount of analog and digital cases, you can also add other appropriate expansion modules to meet the appropriate requirements.
2 control system function control system functions include: equipment operation control and monitor the operating parameters, automatic adjustment of energy, and system fault alarm recording functions such as parameter settings:
(1) equipment operation control unit can be started in three forms, the local launch, remote signal start, start time, in particular: 1) the remote signal and timing signals are shielded case to the local way of start and stop 2) in the regular screening remote signal to allow the case to remotely stop motion 3) allowed under the regular way to start and stop time. Failure in the system without global circumstances, in any way starts, auxiliary equipment, the first open, then open the host. When more than one unit in the compressor, the control system will be based on compressor run time to determine the number of compressor open to allow the compressor unit in the relatively average running time.
There are three start shutdown, startup mode with the corresponding unit. Shutdown, the first compressor unloading, and then stop running. But no matter what boot mode, the local shutdown operations are the highest priority.
(2) Monitoring and control system operating parameters can be monitored during the operation unit operating parameters and equipment operating status, showing the re-To parameters of the trend curve. Such as the cold water outlet temperature, compressor load conditions such as:
(3) auxiliary power unit automatic adjustment in normal operation, the host starts after the completion of the adjustment process into energy. Can select the cold water inlet temperature control or cold water outlet temperature control to determine the unit is under the inlet temperature or outlet temperature to achieve control.
At the entrance or exit temperature control temperature control, the more the actual temperature and the temperature of no value, the decision unit to download. Actual temperature change larger than the set temperature value, the crew on the set; less than the set temperature variation value, the units to download. According to the temperature difference between the two values to determine the cycle length download, big temperature difference between the upload or download a short period, small temperature cycles are uploading or downloading a corresponding increase in the temperature difference between 0.5 ??? can stop the download.
(4) failure alarm control system can record the alarm and records the following conditions. If it is air-cooled chiller control system, there is no cooling water and cooling tower fan corresponding alarm function, but will increase the defrosting and heating operation fault alarm.
Cold water pump failure: the cold water pump start, after delay time, such as cooling water pump chain signal yet that the cold water pump failure alarm.
Disconnection fault: Cold water pump or cooling water pump are activated, water flow delay time to, the flow switch signal yet to come, the water stop alarm.
Antifreeze switch: frost delay time that antifreeze switch signal yet to come, frost alarm.
Cold water temperature alarm: Delay TimeAfter this, such as the cold water outlet temperature is less than 3 ???, cold water temperature alarm.
External cascading failure: time delay, the user external linkage yet to come, external cascading failure.
Compressor Overload: delay time, thermal protection signal yet to come, press thermal overload alarm.
High alarm: delay time, high-voltage protection yet to come, press pressure alarm.
Low alarm: delay time, low-voltage protection yet to come, press Low alarm.
Oil alarm: delay time, oil pressure protection yet to come, press hydraulic alarm.
Sensor fault: delay time, such as the sensor display temperature higher than 200 ???. Sensor fault alarm.
Cooling water pump failure: cooling water pump start delay time, the cooling water pump cooling pump failure alarm chain not yet reached.
Over-current cooling tower fan: fan starts, delay time, over-current protection signal yet to come, fan over-current alarm. There is any fault, switch fault output, the system sound and light alarm. Troubleshooting, the need to manually reset.
(5) system performance, control system can set the following parameters:
Temperature correction value, to amend the actual temperature sensor acquisition, the default value of 0 under the amendment;
Flow switch delay time (default is 3 seconds, down to 0.5 seconds);
Low delay time (default is 5 seconds, the minimum 0.5 seconds);
Hydraulic delay time (default is 50 secondsMinimum 0.5 seconds);
Off delay time (default is 120 seconds);
Compressor minimum run time (default is 120 seconds);
Down to allow the compressor start delay time (default is 480 seconds, the minimum is 300 seconds);
Temperature of the cooling tower fan open (the default is 28 ???, minimum 25 ???, maximum 30 ???);
Body temperature of the cooling tower air (the default is 23 ???, minimum 20 ???, maximum 25 ???);
Cold water inlet temperature (default is 12 ???, the minimum is 10 ???);
Cold water outlet temperature (default is 7 ???, the minimum is 5 ???).
There are mandatory on air-cooled heat pump unit run time of defrosting, defrost initial conditions and end conditions, heating and other operating parameters.
In addition, the system can also modify the controller built-in clock, effectively achieved through the timing control, you can set the time switch machines, automatic timed opening and closing unit. Were set by the switch machine time per day a week, after comparison with the built-in clock automatically run unit. Technical Features 3 small CPM2AH OMRON PLC series has excellent cost performance, the control system composed of the following technical characteristics:
(1) Stable performance CPM2AH series PLC for compact, compact, OMRON company s accumulated experience in production control and strict technical standards to ensure its reliable and stable performance even in harsh industrial environments can still function properly. Even after high temperature test, which makes the PLC can be applied for special occasions.
(2) analog functions using the dedicated TS101/TS102 CPM2AH temperature control module, direct connect PT100 temperature sensor, to enhance the accuracy and reliability of temperature measurement.
(3) communications to provide enhanced CPM2AH built-in RS232C port and RS422 port. OMRON completely open communication protocols can easily host computer remote monitoring function, users can customize their own development of arbitrary communication monitoring system.
(4) high-speed program execution process faster instruction execution speed, making precise control of the process.
(5) a strong expansion of capacity can be increased to 12 channels of analog; system support Device Net protocol, with a strong expansion of capacity, through remote terminals, can be expanded to 256 points, to facilitate the composition of distributed control system.