This is an upgraded version of the Elevator simulator project that was implemented a while ago. To read more about that, click here
In this project, we want to develop hardware/software to implement a 16 Floor Elevator simulator system based on a DELTA PLC and a WEINVIEW HMI device.
The control system has two modes of operation: 1- Remote 2- Local.
In Remote mode: we can control the movement of the Cabin door to be closed or opened by two applied input signals. The angular rotation of the Hand indicator to rotate either Fast or Slow AND Clockwise or Counterclockwise.
- The cabin light can be turned on/off via an input signal when the related signal is activated.
- PLC Simulator generates a pulse signal that goes through two signal transitions: from 0 to 1 and then returns from 1 to 0 anytime the Hand indicator reaches from any previous floor number to the next. The period of the mentioned pulse is about 0.5 seconds. I call this pulse “Every Floor pulse” or EFP” for short.
- PLC simulator generates an output signal which stays “1” as long as the Hand indicator is pointing at Floor # 1 and becomes “0” as soon as the Hand indicator moves away from this position. I call this output signal 1st Floor Pulse or 1FP for short.
- When the Cabin door is closed or opened, output signals D_closed or D_opend become High or Low respectively, and remain at that voltage level as long as the current status of the Cabin door is not changed.
- Two green and red “arrow” images start flashing when the Hand indicator is rotating clockwise (CW) or counterclockwise (CCW) respectively to indicate the direction of an imaginary cabin when it is traveling up or down respectively. The angular speed of rotation of the Cabin is also indicated by two flashing letters “Fast” or “Slow” in red color.
- There is an Image LED at the bottom and rightmost section of the HMI screen, which can be turned on/off via an input signal.
- In Local mode: we can control all previous functions by just touching the corresponding push-button images located at the bottom section of the HMI screen.
- The current floor number is displayed at the top of the Cabin frame.
Figure 1 displays the image we need to design which simulates the traveling direction and speed of the Cabin. It also displays the current status of the Cabin door whether it is Closed or open. It includes a Cabin Lamp image in “yellow” color which can be turned on/off. When the simulator is functioning correctly, we can view how an “analog hand” turns around CW or CCW to indicate the current imaginary location of the Cabin, whether it is parked or is in motion.
Notice that in Figure 1, when the simulator is in Local mode, we can use all image pushbuttons to control the Simulator in Manual mode actually. From left to right, by touching each button, we can perform any of the following functions:
Button 1, places the simulator in either Remote or Local mode.
In Remote mode, all input signals must be provided from the second Master PLC.
In Local mode, the 2nd and 3rd buttons set the speed of the Hand indicator. When any of the buttons mentioned is touched, its color turns to “red” to indicate the Set speed. While the “speed” is set, touching any of either “Up” or “Down” button turns the Hand indicator in either clockwise (CW) or counterclockwise (CCW) direction respectively. Touching and holding any of the Open or Close buttons opens or closes the Cabin door respectively. The last rectangle image represents a Lamp, which can be turned on/off via an input signal.
Figure 2 displays a typical DELTA PLC (Model DVP20SX2), which is used in this project to implement the 16 Floor Elevator simulator system. This brand and model of PLC has 8 digital I/O ports with some analog I/O ports. In this project, we are using only a few I/O digital ports of the PLC. For more information about this model of PLC, you may use the following link:
The table in Figure 3 displays designations of PLC’s I/O to generate the related control signals to communicate with WEINVIEW HMI and the PLC in use.
Input / Output PLC Terminals designation in Figure 2:
Figure 4 shows how to connect the HMI devices to PLC RS485 ports to allow these two devices to establish any handshaking-type communication. We can use the micro USB port of PLC to upload the generated control software from PC to PLC user memory.
Delta model DVP20X211T is a 20-point (8DI + 6 DO + 4AI + 2AO) PLC MPU. It has 6 “NPN open collector” outputs (Y0 to Y5). We need to use four of them, according to Figure 4 in our project.
For an NPN transistor:
The ‘open collector‘ output is the unconnected Collector of an NPN transistor, made available to the external circuitry, that switches to the ground when active. The emitter of the transistor is typically connected to the ground, and the Base is driven by a positive control voltage. This type of output can be used with a pull-up resistor to translate a logic level from one voltage to another or to drive lamps, relays, etc., it has a positive voltage on one terminal and requires a switch to the ground to activate. See Figure 5.
For a PNP transistor:
The ‘open collector’ output is the unconnected Collector of a PNP transistor, made available to the external circuitry that switches to the positive supply when active. The emitter of the transistor is typically connected to the positive supply (or VCC) and the Base is driven by negative control voltage via a resistor. Thus the transistor ‘translates’ the low current low voltage output of a logic device to provide an output that can switch a higher current and voltage to the specified limits of the transistor. This type of output can be used with a pull-down resistor to translate a logic level from one voltage to another or to drive lamps, relays, etc., that have a ground voltage on one terminal and require a switch to a positive voltage to activate. See Figure 6.
The conclusion is that both NPN and PNP open collector outputs exist. NPN is common, both in logic circuits and higher voltage types such as Darlington driver ICs. PNP is more often used in industrial gear, such as proximity switches and PLC outputs, where an input, relay or lamp needs a positive drive signal. Some older industrial stuff uses NPN, but this is generally considered unsafe for control circuits as a ground fault turns things On instead of Off (or blowing a fuse). To remember which is which, NPN switches On to Negative (0V), while PNP switches Onto Positive. Since I use the PNP mode (Switched Positive) option wherever possible, in this case, I have used two Optocouplers to switch two of the PLC outputs (Y0 and Y1 for this application) to the positive voltage. See Figure 7.
Figure 8 shows how to apply the 4N35 IC to switch Y0 and Y1 outputs “on” positive (24 VDC voltage).
With all these explanations about implementing this 16 Floor Simulator system using a DELTA PLC, the most important devices used in this project are:
- A DELTA PLC model DVP20SX2
- The 7-inch Veinview HMI model MT6070iH touch screen
- 2× 4n35 Optocoupler ICS
- Editor software to develop control programs for PLC and HMI display. We can use EasyBuilder 8000 and ISPSoft V2.04 to program the Panel and the PLC respectively.
Both EasyBuilder 8000 and ISPSoft V2.04 can be downloaded from the Internet for free.
We can use two files elevator.isp and elevator_HMI.mtp to program HMI and DELTA devices respectively to get those two devices functional according to the project scope mentioned earlier.
To view the prototype version of this implemented in my office, click here
Two files are developed for this project to create a graphic and control code for the model of the DELTA PLC as specified earlier. These two file names are : 16Floor_HMI.mtp and 16Floor_PLC.isp.
To download the DELTA PLC control program and HMI codes, click here