MC-PLC - Control and processing board for fast applications

Drivers


General features

MC-PLC - MC-PLC

The MC-PLC board is a processor analog and digital signals born to be employed in all those applications normally realized with PLC systems, presenting, in addition, the considerable advantage of having a higher processing speed of at least 10 times.

With the MC-PLC board it is therefore possible to manage applications in which the PLC would be inaccurate because of their inability to follow short signals or that require additional boards for the management of high-speed events.

The board, in its basic version, features the following resources:

  • 8 bidirectional inputs (NPN or PNP) optoisolated, some of which can be associated with particular functions (management of signals with duration of the order of millionths of a second, or measurement of frequencies and / or timing)
  • 8 NPN outputs (open-collector) current with max. 100mA (non-inductive)
  • 3 to 8-bit analog inputs
  • RS232 serial interface (RS485 or alternatively) for the PC connection, to the programming terminal MC-TRM06 or serial printer
  • A non-volatile type memory (EEPROM) of 128 bytes for saving data and configurations (expandable on-board up to 32 Kbytes)
  • 2 synchronous serial lines for the expansion modules (additional inputs / outputs, display, analog / digital converters and digital / analog high precision drives, memory expansion etc.).

Technical details

DIMENSIONS (lenght x width x height) 125 x 77 x 52 mm
FIXTURE DIN guide
CONNECTIONS Extractable screw-on terminals for cable max.1.5 mm
POWER SUPPLY 16-28Vcc 25mA max. (with unconnected inouts and outputs)
OPTO-INSULATED INPUTS AVAILABLE 8 with PNP or NPN logic
PILOT VOLTAGE ON INPUTS 16-30 Vcc (NPN o PNP command) with input resistance 2,2Kohm
OUTPUTS AVAILABLE 8 NPN (standard) or PNP (optional) max.100mA*
ANALOGUE INPUTS AVAILABLE 3 inputs 8 bit with full-scale 5Vdc (resolution 20mV)
SERIAL COMMUNICATION PORTS 1 asynchronous serial port RS232 (or RS485) 2 synchronous serial ports for expansion modules

F.A.Q.

As you can program the functions of a MC-PLC board?

The MC-PLC board derives its speed not only by the use of a high power microprocessor, but also by the implementation of the internal software via particularly efficient programming languages (assembler and C) and able to exploit their full potential.
it is therefore not possible for the user to enter the MC-PLC the desired program. In fact, the MC-PLC board is pre-programmed by Emmeci Electronics according to specific customer requests, which is found to have a card that should only be electrically connected to become functional and which can be, if the specifications require it, parameterized with various devices (switches, PC,
programming terminal MC-TRM06, touch-screen, etc.).

Examples of usage

High speed bottling line with double substratum presence control.

In a bottling and labelling plant of bottles of alcoholic beverages, simultaneous presence of bottle B and the label E to be applied on the cap had to be controlled. Following positive result of the control phase, the system had to start the programmer for sections of adhesive to control gun P, causing hot glue to be placed on the cap of the bottle. The problems to be overcome to fulfil this type of control were 3:

  • The 2 photocells F1 and F2 were never activated simultaneously.
  • The speed of the line could have varied considerably (production could have changed between 3000 and 18000 bottles/hour).
  • Centring precision of the spot of adhesive had to be very high (the spot had to be placed in the centre of the cap with a tolerance of just a few mm)

Solution: the MC-PLC board was used to extend the activation time of photocells F1 and F2, taking it to such a value to allow the simultaneous presence of the 2 signals. When the simultaneous condition was met, the MC-PLC sends the activation command of the spraying cycle to the programmer. The high variability in the speed of the line made it impossible to keep the times of the 2 photocells constant, which, if set for the production rate of 3000 bottles/hour, were too long for that of 18000 bottles/hour (if even just one bottle was missing, the time would not expire, causing the gun to activate accidentally). For this reason, the times associated with the 2 photocells were bound to the speed of the line by reading the encoder already installed (the rise in speed proportionally reduces the duration of the times of the photocells). To make it easier to program the system, the 2 minimum and maximum speed values were entered by means of a teach-in function (reading and saving of the current speed). Thanks to the high processing speed of the MC-PLC board, all these functions can be managed simultaneously, guaranteeing the perfect centring of the spot of adhesive. The illustration shows: B = Bottle on which the label is to be applied. F1 = Bottle presence reading photocell. F2 = Label presence reading photocell. P = Hot-melt gun E = Label to be applied CE = Loader with labels D = Distributor that takes the label from the CE loader to the application position E


Feedback control of the quantity of additive for a plastic film extrusion line.

In a system made up of 3 plastic film extrusion lines (the illustration shows just one of the 3 lines), the quantity of hot additive to be mixed with the PVC to be extruded had to be controlled, bearing in mind the quantity set by the operator and the extrusion speed. For reasons of precision, the amount of additive really dispensed also had to be controlled, compensating the speed of the pump and managing any flow alarms if compensation was not possible. Alarms from the extrusion line and from the additive containment tank also had to be managed, displaying all the anomalies and operating options on the operator panel. The meter used is the gear type with encoder. The speed of the additive pump is adjustable with a standard analogue signal 0-10V. The speed of the extrusion line is given by a standard analogue signal 0-10V. Solution: the system was fulfilled using an electronic section repeated for each of the 3 extrusion lines. Each section consists of an MC-PLC board, combined with an interface with analogue output 0-10V, capable of managing the line and controlling all the signals. The speed of the pump is set considering the data bound to the speed of the extrusion line and the quantity of additive requested and obtaining the rpm from the graph “Flow dispensed = f (rotation speed) “related to the pump, saved in the MC-PLC board. While the system operates, any differences between the theoretic quantity of additive and that really dispensed are compensated by increasing or reducing the rotation speed of the pump. The use of the serial line RS485, suitable for managing a network, enabled the 3 lines to be centralized in one single operator panel. The MC-PLC board, thanks to its numerous peripheral points and its large memory, is able to economically resolve many problems which would be difficult to resolve with other systems.


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