毕业设计(论文)
外文翻译（附外文原文）
学院：机械与控制工程学院
课题名称：基于PLC的施工
升降机控制系统设计
专业(方向)：自动化（控制）
班级：
学生：
指导教师：
日期：
Xiaoling Yang, Qunxiong Zhu, Hong Xu. Design and Practice of an Elevator Control SystemBased on PLC [C/OL].
https://www.doczj.com/doc/1215076045.html,/xpl/articleDetails.jsp?arnumber=4634822,
2008-08-03/2013-05-01.
基于PLC的电梯控制系统的设计与应用
杨晓玲1, 2, 朱群雄1, 徐宏1
1 北京化工大学信息与技术学院中国北京，邮编100029
2 北京联合大学自动化学院中国北京,邮编100101
yxl_lmy@https://www.doczj.com/doc/1215076045.html,, zhuqx@https://www.doczj.com/doc/1215076045.html,
摘要
本文介绍了为一幢居民楼的2个9层电梯而开发的电梯控制系统。该控制系统采用PLC作为控制器，并采用基于“最少等候时间”的并联调度规则使两个电梯运行于并行模式。本文还详细的给出了该PLC控制系统基本结构，控制原理和实现方法，并展示了该系统核心部分的梯形图。该系统不仅具有简单的外围电路，运行结果还表明，它增强了电梯的性能和可靠性。
1 导言
随着建筑技术的发展，大楼变得越来越高，电梯也就成为了高层建筑中垂直运输的重要工具，舒适，高效的把乘客送往目的地。因此，电梯控制系统对于每一个电梯的平稳安全运行是至关重要的。它告诉电梯按什么顺序来启停，何时开关电梯门，是否有重大的安全问题。
传统的电梯电气控制系统是一种继电器控制系统，具有电路复杂，故障率高和可靠性差等缺点，大大影响了电梯的运行质量。因此，受一家企业的委托，我们已经利用PLC技术改进了居民楼中继电器控制电梯的电器控制系统。结果表明，改进后的系统运行可靠，维护方便。
本文详细介绍了该电梯PLC系统的基本结构，控制原理和实现方法。
2 系统结构
该电梯控制系统的目的是让电梯响应乘客的要求并做出正确的运动。它主要分为两个部分：
2.1 电力驱动系统
这里，电力驱动系统主要包括：电梯轿厢，牵引电动机，电梯门马达，制动机构
和相关的开关电路。
这里，我们采用一种新的LC型交流接触器代替旧的，并使用PLC的触点来代替大量的中继器。而牵引电动机的线路则予以保留。这样，原来控制柜体积大，噪声大的缺点就被解决了
2.2 信号控制系统
电梯的控制信号大多是由PLC实现的。输入信号有：运行模式信号，操作控制信号，轿厢指令信号，厅门呼梯信号，安全/保护信号，梯门打/关信号和平整信号等。电梯系统的所有控制功能都是由PLC程序完成的，例如：登记，显示，取消轿厢指令和厅门呼梯，判断电梯位置，选择电梯的运动方向和层等。图1中显示了电梯的PLC控制系统框图
图1 PLC信号控制系统图
2.3 需求
开发这个控制系统的目的是去控制一幢居民楼的2个9层电梯。
对于每一个电梯，每一层上都安装了一个传感器。我们能利用这些传感器去了解电梯轿厢的实时位置。电梯轿厢的门是靠门电机来实现开启和闭合的。电梯的门上安装有2个传感器，一个用于通知控制系统电梯门的位置，另一个可以在电梯门关闭的时候侦测物体。电梯的上下运动则是通过牵引电动机来控制的。
除了第一层和最高层之外，每一层都有一对方向灯指明电梯是在上升还是下降。
每个楼层，都有一个7段LED用于显示电梯轿厢的当前位置。
明确基本需求是开发这个电梯控制系统的第一步，简单来说，这两个电梯有以下
行为：
1)、一个电梯单独运行
一般来说，电梯有三个运行状态：正常模式，火灾保护模式和维护模式。维护模式具有最高的优先级，只有不在维护模式时，其他运行模式才能执行。其次是火灾保护模式，当火险开关作用时时，电梯必须立即回到底层或者基站。而火险开关复位后，电梯就应该回到正常运行模式。在正常操作模式下，控制系统的基本任务是指挥每个电梯上下移动，停止启动，打开和关闭电梯门。但其中也有如下的一些限制因素：每个电梯都有一组9个按钮放置在轿厢的控制面板上，每一个对应一层楼。当按钮被按下时，按钮就会发光并且使电梯向相应的楼层运动，当电梯到达指定楼层之后，按钮的光芒就会消失。
除了底层和顶层之外，每个楼层的控制面板上都有两个按钮。一个按钮请求电梯上升，另一个请求电梯下降。按钮在按下去的状态下会发光。当电梯来到乘客所在楼层时，按钮的发光消失，然后朝着期望的方向运行。
电梯轿厢的控制面板和楼层的控制面板上的按钮都是用来控制电梯运行方向的。
电梯不能漏过任何楼层，如果那个楼层有乘客想要出去。
电梯不能在没有乘客要出去的楼层停止
直到将所有当前方向的乘客送达之前，电梯不能改变方向，并且，当电梯在相反方向运行时，厅门呼梯不能得到响应。
如果电梯没有接到任何需求，则停在当前层，并保持电梯门关闭。
2)、两个电梯并联运行
在这种情况下，两个电梯同时为大楼服务，从早上7点到9点，再从下午5点到7点。
当电梯到达某一层，它将测试是否需要停止，当必须停止时，电梯则会停在这一层。
与此同时，为了平衡停止的次数，两个电梯的操作还将遵循一定的调度原则。
电梯不会停止在一个已经有另一个电梯停着的楼层。
正常运行模式的电梯是由电力驱动系统和逻辑控制系统共同操控的。
3 软件设计
由于呼叫时间，呼叫地点，乘客目的地的随机性质，电梯控制系统是一个典型的实时，随机逻辑控制系统。在这里，我们采用集选控制方法与西门子PLC S7 - 200 CPU226及其扩展模块。系统中有46输入节点和46个输出节点。这里I/O节点详情见表1和表2 。
表1 输入节点
描述地址
1-8 层向上厅门呼梯I0.0-I0.7
2-9 层向下厅门呼梯I1.0-I1.7
1-9 层轿厢指令I2.0-I2.7, I3.0
1-9 抵达传感器I3.1-I3.7, I4.0-I4.1
电梯门打开按钮I4.2
电梯门关闭按钮I4.3
电梯门关闭位置开关I4.4
电梯门打开位置开关I4.5
向上调平传感器I4.6
向下调平传感器I4.7
火警开关I5.0
驱动器操作开关I5.1
电梯门控制面板开关I5.2
超载I5.3
被迫速度变化开关I5.4
满载I5.5
表2 输出节点
描述地址
1-8 层向上厅门呼梯灯Q0.0-Q0.7
2-9 层向下厅门呼梯灯Q1.0-Q1.7
1-9 层轿厢指令灯Q2.0-Q2.7, Q3.0
向上运动指示灯Q3.1
向下运动指示灯Q3.2
电梯位置的7段LED显示器Q3.3-Q3.7 Q4.0-4.1
电梯门正在打开Q4.2
电梯门正在关闭Q4.3
向上运动Q4.4
向下运动Q4.5
满载灯Q4.6
高速运行Q4.7
低速运行Q5.0
加速Q5.1
减速Q5.2-Q5.4
警告发声器Q5.5
关于软件设计，我们采用模块化的方法来写梯形图程序。模块之间的信息传输则依靠PLC的中间寄存器来实现。
整个程序主要由10个模块组成：厅门呼梯登记和显示模块，轿厢指令登记和显示模块，信号组合模块，厅门呼梯取消模块，电梯位置显示模块，楼层选择模块，移动方向控制模块，电梯门开启/关闭模块，维护操作模块和并行模式下的调度模块。
以下是几个典型模块的设计描述：
3.1 厅门呼梯登记和显示模块
在电梯中有两种呼叫模式：厅门呼梯和轿厢指令。当有人按下楼层控制面板的按钮，信号就会被登记，相应的灯就点亮。这就是厅门呼梯登记。当乘客按下电梯轿厢内的一个按钮，信号将被登记，与之相应的灯照亮。这就是轿厢指令登记。图2显示
了向上厅门呼梯登记和显示的梯形图，自锁原则用来确保呼叫不断的显示。
图2 向上厅门呼梯登记与显示
3.2 呼叫的集选
这里使用了集选控制原则。就像图3中显示的那样，M5.1－M5.7，M6.0和M6.1是辅助寄存器。它们分别用来表示从一层到九层的停止请求信号。辅助继电器6.2指明电梯驱动器的操作信号。如果在某一层有一个呼叫，相应楼层的停止信号将被输出。当电梯被驱动器运行时，厅门呼梯将无法实现。电梯无法漏过乘客要下车的任何一层。
3.3 呼叫取消
这个模块使电梯能响应与轿厢运动方向相同的厅门呼梯指令，当厅门呼梯已经得到响应，它的登记将被取消。电梯向上厅门呼梯指令取消的梯形图如图4。
图3 呼梯的组合
图4 向上呼梯的取消
在图4中，辅助寄存器M4.0是电梯向上运动的标志，当电梯的当前运动是向上，则M4.0的触电是关闭的，反之则是打开的。M0.1到M0.7分别对应2楼到8楼的轿厢停止指令。
这个程序由两个功能：
1)、当电梯向下运动时，使电梯能响应正常的向下厅门呼梯指令。当指令响应之后，则取消该指令的登记
2)、当电梯向上运动时，相应楼层向下的厅门呼梯指令不响应并保留指令的登记
向下厅门呼梯的取消则与向上的正好相反。
3.4电梯的方向
电梯可能向上或者向下运动，取决于厅门呼梯和轿厢指令，图5中的梯形图是电梯向上运动的情况。
图5 电梯向上运动
图5表明，当呼叫的楼层比当前电梯所在楼层高时，电梯将向上运动。辅助寄存器M4.0被用作电梯向上运动的标志。当电梯向上运动，向上运动的指示灯就被点亮。M4.0也就被连接上了。当电梯到达顶层时，向上运动的指示灯熄灭，计时器开始运行。0.2秒之后，M4.0被断开。向上运动显示停止。这里M4.0代替了Q3.1，用来确保取消的可靠性。
3.5 电梯的楼层停止
图6的是电梯楼层停止功能的梯形图。
如图6，M6.4是楼层停止信号的标志，驱动器传送楼层停止信号到M6.6，火警开关传送火警信号给M7.0，M6.7显示速度改变信号。这些接触器中的任何一个工作，楼层停止信号就会发送。
4 最小等待时间算法
在电梯系统中，通常有两种控制任务，一个是基本的控制功能，用于指挥电梯上下运动，启停，电梯门的开合。另一个则是用来控制一组多个电梯。
作用于厅门呼梯和轿厢指令的一组控制系统的最主要的需求应该包括：对大楼的每一层都提供同样的服务；最小化乘客等待的时间；最小化乘客在电梯轿厢内的时间；
在规定时间内为尽可能多的乘客服务[1]。
图6 电梯的楼层停止
电梯的组控制有许多种算法，例如最邻近算法[2]，这种算法下，电梯总是在下一步先响应最近的要求；分区算法[3]通过分析不同楼层的电梯需求情况来调度电梯；奇偶算法使一个电梯仅仅为基数层服务，而另一个则只为偶数层服务。
最邻近算法使相邻的两个要求之间电梯的空运行最小。从而得到非常小的平均等待时间。但个别的等待时间可能非常长。分区算法通常适用于大楼中流量非常大的情况下，例如午餐时候的办公室大楼。
相对于办公楼和购物商场，居民楼的电梯使用人流量是比较小的，而且各层之间人流比较平均。其次，人们通常认为电梯就是一种纯粹的工具，对于他们中的大部分人来说乘坐电梯时间就是在等待。此外，试图满足所有需求也是不切合实际的。基于以上的原因，我们采用最小等待时间的算法来实现2个电梯的并行运行[4]。
4.1 预估函数
最小等待时间算法的目的是预测每个电梯对所有呼叫的响应时间。然后选出响应时间最短的电梯来服务。
当有一个呼叫需要响应时，系统根据等式(1),(2)算出每一个电梯的函数值。
J(*)=Min[J(1),J(2),…,J(n)] (1)
J(i)=Tr(i)+KTd(i)+KTo(i) i=1,2,...,n (2) J(i)是每个电梯的估算指数，Tr(i)表明电梯从当前层运行到最近呼梯的目的地的时间。To(i)则是电梯停止时额外的加速和减速的时间。Td(i)指乘客进入和离开电梯平均所花的时间。K是厅门呼梯和轿厢指令的和。但是厅门呼梯和轿厢指令对应同一楼层，因此只计算一次。
4.2 最小等待时间的计算
在等式2中，K是一个定值，To 和Td可以通过统计的方法获得。Tr = T*L，T 表示电梯经过一个楼层的平均时间，L表示从当前楼层到厅门呼梯楼层之间的楼层数。
为了计算L的值，我们假设两个电梯分别为A和B。Y A,Y B分别表示电梯A和B 的当前层。当厅门呼梯键按下，H是一个相应的关键值。H=厅门呼梯所在层的层数。
我们为PLC的实现定义四个表：向上厅门呼梯登记表，向下厅门呼梯登记表，轿厢指令登记表A和B，当某个呼叫按钮被按下时，楼层值被记录在相应的表单中。
以电梯A为例，定义变量M A, M B和M W。M A和M B分别代表电梯A或B相同运动方向的轿厢指令的极值。
当电梯A向上运动，使M A等于轿厢指令登记表A的最大值，当电梯A向下运动时，设M A为轿厢指令登记表A的最小值。
M W代表与A方向相同的厅门呼梯的极值。
当电梯A向上运动，并且向上的厅门呼梯值大于等于Y A，则M W置0，否则，M W等于向上的厅门呼梯登记表A中的最小值。当电梯A向下运动，并且向上的厅门呼梯值小于等于Y A，M W置0，否则，M W的值等于向下厅门呼梯登记表A中的最大值。
这样，我们就能根据Y A，H，M A和M W来确定L的值了，总共分为三种情况：
1)、当厅门呼梯的方向与电梯A运动方向相反时：
L=|Y A-M A|+|M A-H| (3)
2)、当厅门呼梯的方向与电梯A运动方向相同，并且厅门呼梯先于电梯A发出指令：
L=|Y A-H| (4)
3)、当厅门呼梯的方向与电梯A运动方向相同，并且电梯A先向该方向运动：
L=|Y A-M A |+|M A-M W|+|H-M W| (5) 这样，第i层楼的最小等待时间就能按照等式6来计算了：
Time(i)=TL(i)+KTd(i)+KTo(i) i=1,2,...,n (6) 当电梯运行时呼叫改变，系统会计算每个电梯的最小等待时间，然后分配当前的呼叫请求到那个拥有较小值的电梯，如果每个电梯拥有相同的值，则优先分配给
A。
当有一个电梯发生故障或者不能服务时，系统将会跳出调度算法，而进入单一运行模式。
4.3 算法的实现
与单一电梯的运行模式相比，并行运行模式的区别主要在于对厅门呼梯的处理方法。前者使用集选控制方法，后者使用调度原则与集选控制方法相结合的方式。
这个系统要控制一幢九层大楼，所以我们选择两个Siemens S7-200 PLC(CPU226)以及它的扩展模块去分别控制一个电梯，并使用PPI协议来实现两个PLC之间的交流。
PPI协议采用主从交流模式，所以我们将A电梯定义为主电梯，B电梯为从电梯。通过交流程序，两个PLC能够交换信息：例如当前位置，厅门呼梯还是轿厢指令，运动方向等等。然后使用最小等待时间算法，使两部电梯的运行得到优化。
图7为A电梯轿厢指令极值计算的梯形图
在图7中，VB121～VB130是电梯A每一层轿厢呼叫的寄存器地址。Q3.1是电梯向上运动的指示灯。轿厢指令的极值保存在VB120中。
图7 电梯A的轿厢指令最大值计算
5 结论
这篇文章中，我们已经通过使用PLC来改进了一个旧的电梯控制系统，并且实现了两个电梯的组控制。新的控制系统已经使用一年，它的操作方案如下：
1)、低峰时
从早上7点到9点，这时关心人们离开大楼
2)、高峰时
从下午5点到7点，这时关心人们进入大楼
3)、其他
从早上6点到晚上12点的所有时间，除了上述两段时间外，这些时候仅有一部电梯运行。
由于改进之前系统并非并行模式，因此在高峰期和低谷期的平均等待时间和最大等待时间都长于改进后的系统。实践结果表明，改进后的系统表现好于改进之前。
参考文献
[1] Ricardo Gudwin, Fernando Gomide, Marcio. A Fuzzy Elevator Group Controller With
Linear Context Adaptation[M]. IEEE World Congress on Computational Intelligence, 2006.
[2] Philipp Friese, Jorg Rambau. Online-optimization of multi-elevator transport systems
with reoptimization algorithms based on set-partitioning models[M]. Discrete Applied Mathematics, 2005.
[3] Zheng Yanjun, Zhang Huiqiao, Ye Qingtai, Zhu Changming. The Research on Elevator
Dynamic Zoning Algorithm and It's Genetic Evolution[M]. Computer Engineering and Applications, 2008.
[4] Xiaodong Zhu, Qingshan Zeng. A Elevator Group Control Algorithm for Minimum
Waiting Time Based On PLC[M]. Journal of Hoisting and Conveying Machiner, 2001.
Design and Practice of an Elevator Control System Based on
PLC
Xiaoling Yang1, 2, Qunxiong Zhu1, Hong Xu1
1 College of Information Science &Technology,
Beijing University of Chemical Technology, Beijing 100029, China
2 Automation College of Beijing Union University,Beijing,100101, China
yxl_lmy@ https://www.doczj.com/doc/1215076045.html,,zhuqx@https://www.doczj.com/doc/1215076045.html,,
Abstract
This paper describes the development of 2 nine-storey elevators control system for a residential building. The control system adopts PLC as controller, and uses a parallel connection dispatching rule based on "minimum waiting time" to run 2 elevators in parallel mode. The paper gives the basic structure, control principle and realization method of the PLC control system in detail. It also presents the ladder diagram of the key aspects of the system. The system has simple peripheral circuit and the operation result showed that it enhanced the reliability and performance of the elevators.
1.Introduction
With the development of architecture technology, the building is taller and taller and elevators become important vertical transportation vehicles in high-rise buildings. They are responsible to transport passengers, living, working or visiting in the building, comfortable and efficiently to their destinations. So the elevator control system is essential in the smooth and safe operation of each elevator. It tells the elevator in what order to stop at floors, when to open or close the door and if there is a safety-critical issue.
The traditional electrical control system of elevators is a relay-controlled system. It has the disadvantages such as complicated circuits, high fault ratio and poor dependability; and greatly affects the elevator’s running quality. Therefore, entrusted by an enterprise, we have improved electrical control system of a relay-controlledelevator in a residential building by using PLC. The result showed that the reformed system is reliable in operation and easy for maintenance.
This paper introduces the basic structure, control principle and realization method of the elevator PLC control system in detail.
2.System structure
The purpose of the elevator control system is to manage movement of an elevator in
response to user’s requests. It is mainly composed of 2 parts:
2.1 Electric power driving system
The electric power driving system includes: the elevator car, the traction motor, door motor, brake mechanism and relevant switch circuits.
Here we adopted a new type of LC series AC contactors to replace the old ones, and used PLC’s contacts to sub stitute the plenty of intermediate relays. The circuits of traction motor are reserved. Thus the original control cabinet’s disadvantages, such as big volume and high noise are overcome efficiently.
2.2 Signal control system
The elevator’s control signals are mostly realized by PLC. The input signals are: operation modes, operation control signals, car-calls, hall-calls, safety/protect signals, door open/close signal and leveling signal, etc. All control functions of the elevator system are realized by PLC program, such as registration, display and elimination of hall-calls or car-calls, position judgment of elevator car, choose layer and direction selection of the elevator, etc. The PLC signal control system diagram of elevator is showed in Figure 1.
Figure 1 PLC signal control system diagram
2.3 Requirements
The goal of the development of the control system is to control 2 elevators in a 9-storey residential building.
For each elevator, there is a sensor located at every floor. We can use these sensors to locate the current position of the elevator car. The elevator car door can be opened and closed by a door motor. There are 2 sensors on the door that can inform the control system about the door’s position. There is another sensor on the door can detect objects when the
door is closing. The elevator car’s up or down movement is controlled by a traction motor.
Every floor, except the first and the top floor, has a pair of direction lamps indicating that the elevator is moving up or down.
Every floor, has a seven segment LED to display the current location of the elevator car.
The first step for the development of the elevator control is to define the basic requirements. Informally, the elevators behavior is defined as follows.
(1)Running with a single elevator
Generally, an elevator has three operation states: normal mode, fire-protection mode and maintenance mode. The maintenance mode has the highest priority. Only the maintenance mode is canceled can the other operation modes be implemented. The next is fire-protection mode, the elevator must return to the bottom floor or base station immediately when the fire switch acts. The elevator should turn to normal operation mode when the fire switch is reset. Under normal operation mode, the control system’s basic task is to command each elevator to move up or down, to stop or start and to open and close the door. But is has some constraints as follows:
Each elevator has a set of 9 buttons on the car control panel, one for each floor. These buttons illuminate when they are pressed and cause the elevator to visit the corresponding floor. The illumination is canceled when the corresponding floor is visited by the elevator.
Each floor, except the first and the top floor, has two buttons on the floor control panel, one to request an upelevator, one to request a down-elevator. These buttons illuminate when they are pressed. The illumination is canceled when an elevator visits the floor, then moves in the desired direction.
The buttons on the car control panel or the floor control panel are used to control the elevator’s motion.
The elevator cannot pass a floor if a passenger wants to get off there.
The elevator cannot stop at a floor unless someone wants to get off there.
The elevator cannot change direction until it has served all onboard passengers traveling in the current direction, and a hall call cannot be served by a car going in the reverse direction.
If an elevator has no requests, it remains at its current floor with its doors closed.
(2)Parallel running with two elevators
In this situation, there are two elevators to serve the building simultaneously. It runs at 7am to 9am and 5pm to 7pm every day.
When an elevator reaches a level, it will test if the stop is required or not. It will stop at this level when the stop is required.
At the same time, to balance the number of stops, the operation of two elevators will follow a certain dispatching principle.
An elevator doesn’t stop at a floor if another car is already stopping, or has been stopped there.
The normal operation of elevators is implemented by cooperation of its electric power driving system and logic control system.
3. Software design
Due to the random nature of call time, call locations and the destination of passengers, the elevator control system is a typical real-time, random logic control system. Here we adopted collective selective control method with siemens PLC S7-200 CPU226 and its extension modules. There are 46 input points and 46 output points in the system. The I/O points are showed in Table1.
Table 1 I/O address distribute
Input points Output points
description address description address 1-8 floor up hall-call I0.0-I0.7 1-8 floor up hall-call lamp Q0.0-Q0.7 2-9 floor down hall-call I1.0-I1.7 2-9 floor down hall-call lamp Q1.0-Q1.7
1-9 floor car-call I2.0-I2.7, I3.0 1-9 floor car-call lamp Q2.0-Q2.7,
Q3.0
1-9 arrival sensor I3.1-I3.7,
I4.0-I4.1
up moving lamp Q3.1
door open button I4.2 down moving lamp Q3.2
door close button I4.3 Seven segment LED display of Q3.3-Q3.7 door close location switch I4.4 elevator’s position Q4.0-4.1 door open location switch I4.5 door opening Q4.2 up leveling sensor I4.6 door closing Q4.3
down leveling sensor I4.7 up moving Q4.4 fire switch I5.0 down moving Q4.5 driver operation switch I5.1 full load lamp Q4.6 touch panel switch of car door I5.2 high speed operation Q4.7 overload I5.3 low speed operation Q5.0 Forced speed changing switch I5.4 acceleration of starting Q5.1 full load I5.5 deceleration of braking Q5.2-Q5.4
alarm beeper Q5.5 About software designing, we adopt the modularized method to write ladder diagram programs. The information transmission between modules is achieved by intermediate register bit of PLC.
The whole program is mainly composed of 10 modules: hall-call registration and display module, car-call registration and display module, the signal combination module, the hall-call cancel module, the elevator-location display module, the floor selection module, the moving direction control module, the door open/close module, the maintenance operation module and the dispatching module under parallel running mode.
The design of the typical modules is described as follows:
3.1 Hall-call registration and display
There are two kinds of calls in an elevator: hall-call and car-call. When someone presses a button on the floor control panel, the signal will be registered and the corresponding lamp will illuminate. This is called hall-call registration.
When a passenger presses a button in the elevator car, the signal will be registered and with the corresponding lamp illuminated. This is called car-call registration.
Figure2 shows the ladder diagram of up hall-calls registration and display. The self-lock principle is used to guarantee the calls’ continuous display.
Figure 2 up hall-call registration and display
3.2 The collective selection of the calls
Here the collective selection control rules are used. As showed in Figure3, M5.1-M5.7, M6.0 and M6.1 are auxiliary relays in PLC. They denote the stopping request signal of 1st to 9th floor res pectively. The auxiliary relay M6.2 denotes the elevator driver’s operation signal. When there is a call in a certain floor, the stopping signal of corresponding floor will output. When the elevator is operated by the driver, the hall-calls will not be served. And the elevator cannot pass a floor at which a passenger wishes to alight.
3.3 The cancellation of the calls
The program of this module can make the elevator response the hall-calls which have the same direction as the car’s current direction, and wh en a hall-call is served, its registration will be canceled. The ladder diagram of up hall-calls’ cancellation is showed in Figure4.
Figure 3 The combination of the calls
Figure 4 The cancellation of up calls
In Figure4, the auxiliary relay M4.0 is the up moving flag of the elevator. When the
current direction of the elevator is up, M4.0’s contacts are closed; on the contrary, when the current direction of the elevator is down, M4.0’s contacts are opened. M0.1 to M0.7 denotes the car-calls’ stopping request signal of floor 2 to floor 8 respectively.
This program has two functions:
(1) Make the elevator response the normal down hall-calls when it is moving down, and when a down hall-call is served, its registration is canceled.
(2) When the elevator is moving up, the corresponding floor’s down hall-call it passing by is not served and the registration is remained.
The cancellation of down hall-calls is reversed with up hall-calls.
3.4 Elevator’s direction
The elevator may be moving up or down, depending on the combination of hall-calls and car-calls. The following ladder diagram in Fig.5 illustrates that the elevator will move up.
Figure 5 Up moving of the elevator
Figure5 shows that when the calls corresponding floor is higher than the elevator’s current location, the elevator will go up. Here the auxiliary relay M4.0 is used as the up-moving flag. When the elevator is moving up, the up-moving lamp is illuminated, so
the M4.0 is connected on. When the elevator arrives the top floor, the up-moving lamp is off and the timer starts. After 0.2s, the M4.0 is disconnected, the up-moving display is off. Here we used M4.0 to replace Q3.1 which can ensure the cancellation’s reliability.
3.5 Elevator’s floor-stopping
Figure6 shows the ladd er diagram of the elevator’s floor-stopping function.
As showed in Figure6, M6.4 is the flag of floor-stopping signal. M6.6 is the floor-stopping signal sent by the driver. M7.0 is the fire signal sent by the fire switch. And M6.7 is the forced speed changing signal. When either of these contacts act, the system should send out the floor-stopping signal.
Figure 6 The elevator’s floor-stopping