求译求译Whenthelevelisbetweenthesensors,thesystemistokeeponepumpon,alternatingthepumpsonsuccessiveentriesintothe“between”region.Fig.1illustratesthebasiccomponentsofrelayladderlogic.Averticalrailtotheleftsup

Question

求译求译
When the level is between the sensors,the system is to keep one pump on,alternating the pumps on successive entries into the “between” region.
Fig.1 illustrates the basic components of relay ladder logic.A vertical rail to the left supplies “energy” (i.e.“hot” flow) to all crossing rungs of the ladder.The “energy” flows from left to right only,following vertical paths where provided.Contacts (emulating contacts of a relay panel) along the rungs may interrupt the “hot” flow.The contacts are controlled by inputs such as “belowl” and “below2”,and by stored state variables.A label under each contact identifies the controlling value.
Fig.2 identifies the symbols representing the two types of contacts used.Normally open contacts open,terminating a “hot” path,when the controlling value is FALSE,while normally closed contacts do so when the controlling value is TRUE.
Boolean state and output variables of the relay ladder controller are represented by “coils”,typically confined to the rightmost column of the ladder.The value of the variable is considered TRUE on cycles following those in which “hot” flow reaches the coil.State variables control contacts in the ladder.Their values are also available as outputs.Other coil variables,such as “pumpl” and “pump2”,are pure outputs,controlling no contacts.
Ladder topology is a direct graphic analog of combinational gate logic.Contacts in series represent
the AND operation,and parallel flow branches represents OR.Normally closed contacts implement the NOT operator and complemented variables.Sets of rows feeding a single coil,variously called rungs or networks,are equivalent to logical equations.
When contacts set by input and state values are held constant while ladder flow is recomputed,a relay logic solving PLC emulates a synchronous digital circuit.PLCs can also be operated in “sequential mode”,in which hot flow at a coil in the computed flow is immediately applied to the value of the corresponding state variable,effecting the opening and closing of contacts controlled by the variable which are encountered later in the same scan.In examining solving methods,we only consider synchronous operation.Synchronous operation is the more difficult for the solver,which must maintain a currently applied value and a “next cycle” value of the variable,and substitute values between cycles.
The synchronous RLL model is easier to program reliably,since the order of network evaluation has no role in determining behavior.As mentioned earlier,extreme efficiency of the solver can permit elimination of scan control logic,making synchronous operation possible.

Answer 1

当水平在传感器之间时,系统是保留一个泵浦,交替泵浦在连续词条入“在”区域之间.1说明中转梯子逻辑基本成分.垂直的路轨对左供应“能量” (即“热的”流程)到梯子的所有横穿阶.“能量”只从左到右流动,走垂直的道路,假设.联络(看齐中转盘区的联络)沿阶也许中断“热的”流程.联络控制的由输入例如“belowl”和“below2”和是由被存放的状态变量.一个标签在每联络之下辨认控制价值.2辨认代表联络的二个类型标志使用.通常开放联络开始,终止“热的”道路,当控制价值是错误的时,而通常闭合的联络如此,当控制价值是真实的时.中转梯子控制器的布尔状态和输出变量由“卷”代表,典型地被限制对梯子的最右的专栏.可变物的价值被认为真实在跟随“热的”流程到达卷的那些的周期.状态变量控制联络在梯子.他们的价值也是可利用的作为产品.其他盘绕可变物,例如“pumpl”,并且“pump2”,不是纯净的产品,控制联络.梯子拓扑结构是组合门逻辑一个直接图表类似物.联络在系列代表 和操作和并行流分支代表或.通常闭合的联络实施不是操作员和被补全的可变物.列哺养唯一卷,不同地称阶或网络的套,与逻辑等式是等效的.当联络由输入时设置,并且状态价值被拿着恒定,当梯子流程重新计算时,解决PLC的中转逻辑看齐一条同步数字电路.PLCs在“连续方式下”可能也被管理,热的流程在卷在计算流程立刻被申请于对应态可变物的价值,影响可变物控制的联络开头和closing在同一扫瞄以后遇到.在审查的解决的方法,我们只考虑同步操作.同步操作为解难题者是困难的,必须坚持当前被运用的价值和可变物的“下个周期”价值,并且替代在周期范围的价值.同步RLL模型是更加容易可靠地编程,因为网络评估命令没有在确定行为的角色.作为解难题者的被提及的更早,极端效率可能允许扫瞄控制逻辑的排除,使同步操作成为可能.