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1.发明授权
公开(公告)号：US4729125A
公开(公告)日：1988-03-01
申请号：US764913
申请日：1985-08-12
CPC分类号： G08C19/02
摘要： A serial communication interface establishes communication to the microprocessor of a transmitter, from a current loop which is powered by a power supply. The microprocessor outputs an analog signal corresponding to a process variable and also can receive a serial communication voltage pulse signal. The analog signal is applied to a current regulating circuit which draws current from the power supply onto the current loop in an amount which is proportional to the process variable. A comparator in the form of an operational amplifier has an output connected to the microprocessor for applying the serial communication voltage pulse signal to the microprocessor. The comparator has one input which is held at a slight negative voltage and another input which is connected to a line of the current loop connected to the negative terminal of the power supply. To establish communication from the current loop to the microprocessor, voltage on the current loop is modulated by a small amount to generate small voltage pulses which are applied to a positive input of the comparator. The comparator amplifies the small voltage pulses into larger voltage pulses which are then applied to the input of the microprocessor to establish digital communication with the microprocessor. In this way the analog signal on the current loop can be maintained simultaneously with digital communication between the loop and the microprocessor.
摘要翻译： 串行通信接口从由电源供电的电流环路建立到发射机的微处理器的通信。 微处理器输出对应于过程变量的模拟信号，并且还可以接收串行通信电压脉冲信号。 模拟信号被施加到电流调节电路，该电流调节电路以与过程变量成比例的量将电流从电源吸取到电流回路上。 运算放大器形式的比较器具有连接到微处理器的输出端，用于将串行通信电压脉冲信号施加到微处理器。 比较器具有一个保持在轻微的负电压的输入端，另一个输入端连接到与电源的负极端子连接的电流回路的一条线路上。 为了建立从当前环路到微处理器的通信，电流环路上的电压被调制少量，以产生施加到比较器的正输入端的小电压脉冲。 比较器将小电压脉冲放大到更大的电压脉冲，然后将其施加到微处理器的输入端以与微处理器建立数字通信。 以这种方式，电流环路上的模拟信号可以与环路和微处理器之间的数字通信同时保持。
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2.发明授权
公开(公告)号：US4691328A
公开(公告)日：1987-09-01
申请号：US764915
申请日：1985-08-12
CPC分类号： G08C19/02
摘要： An on-line serial communication interface is established from a digital circuit such as a computer or hand held terminal, to a current loop which has lines for connecting a transmitter to a power supply. The interface includes a diode which is connected in series with one of the lines of the current loop. The diode is connected in parallel to the source and drain of a FET. The control gate of the FET is connected to the output of a differential amplifier who receives as one of its inputs, a digital voltage pulse signal from the digital circuit. The other input of the amplifier is held at a selected voltage so that voltage pulses are output from the amplifier when the digital circuit generates its voltage pulses. This turns the FET on and off in synchronism with the voltage pulses, thus cutting the diode in and out of series with the line of the current loop. With the FET in its non-conducting off condition, the diode has a small voltage drop thereacross. This does not effect the current on the current loop. With the FET conducting and in its on state, the diode is cut out and its voltage drop is applied to the transmitter which is connected to the current loop. Communication can thus be established with the transmitter while again avoiding any interruption in the current on the current loop.
摘要翻译： 从诸如计算机或手持终端的数字电路建立在线串行通信接口到具有用于将发射机连接到电源的线路的电流回路。 该接口包括与电流回路中的一条线串联连接的二极管。 二极管与FET的源极和漏极并联连接。 FET的控制栅极连接到接收作为其输入之一的差分放大器的输出端，数字电路的数字电压脉冲信号。 放大器的另一个输入端保持选定的电压，使数字电路产生电压脉冲时，从放大器输出电压脉冲。 这样就可以与电压脉冲同步地打开和关闭FET，从而将二极管与电流回路的线路串联切断。 当FET处于非导通关断状态时，二极管的电压降很小。 这不影响当前循环中的电流。 FET导通并处于导通状态，二极管被切断，其电压降被施加到连接到电流环路的发射器。 因此可以与发射机建立通信，同时又避免电流环路中的电流的任何中断。
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3.发明授权On-line serial communication interface from a current loop to a computer and/or terminal 失效在线串行通信接口，从当前循环到计算机和/或终端
公开(公告)号：US4816703A
公开(公告)日：1989-03-28
申请号：US764914
申请日：1985-08-12
CPC分类号： G08C19/02
摘要： An on-line serial communication interface is established from the transmitter of a two line current loop transmitter to a digital circuit such as a computer or hand-held terminal which receives and processes digital voltage pulses. The interface includes a comparator having a positive terminal connected by a capacitor to one of the current lines, and a negative terminal connected to a source of small positive voltage. The output of the comparator is connected to an input port of the digital device. The transmitter modulates the current on the current loop by a small amount with respect to the analog current communicated by the transmitter. This generates voltage pulses in the capacitor which are compared to the selected voltage and are amplified to form large pulses used for communication with the computer or hand-held terminal.
摘要翻译： 从两线电流环路发射机的发射机建立到线路串行通信接口到数字电路，例如接收和处理数字电压脉冲的计算机或手持终端。 该接口包括一个比较器，其具有通过电容器连接到一条电流线的正极端子，以及连接到小的正电压源的负极端子。 比较器的输出连接到数字设备的输入端口。 发射机相对于由发射机通信的模拟电流调制电流环路上的电流少量。 这产生电容器中的电压脉冲，其与所选择的电压相比较，并被放大以形成用于与计算机或手持终端通信的大脉冲。
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公开(公告)号：US4655074A
公开(公告)日：1987-04-07
申请号：US764916
申请日：1985-08-12
CPC分类号： G01L27/005
摘要： A pressure transmitter assembly comprises a pressure transducer having a pair of inputs each connected to a separate pressure line. A valve is connected in each pressure line. A pressure equalizing line is connected between the pressure lines at a point between the valves and the pressure transducer. The pressure equalization line is provided with an equalization valve. All three valves are connected to a switching circuit which is controlled by a microprocessor. The switching circuit functions to open both of the valves in the pressure lines while closing the equalizing valves so that the pressure transducer is exposed to two separate pressure and generates a signal corresponding to a difference in two separate pressures. To zero the transducer and recalibrate the transmitter, the low pressure line valve is closed while the equalizing valve is opened. This equalizes the pressure between the two pressure lines so that any signal from the transducer corresponds to a zero pressure difference value.
摘要翻译： 压力变送器组件包括具有一对输入的压力传感器，每个输入端连接到单独的压力线。 每个压力管路连接一个阀门。 在阀和压力传感器之间的点处，压力线之间连接有均压线。 压力平衡管路设有均压阀。 所有三个阀都连接到由微处理器控制的开关电路。 切换电路用于打开压力管路中的两个阀门，同时关闭均压阀，使得压力传感器暴露于两个分开的压力，并产生对应于两个分离压力差的信号。 要使传感器归零并重新校准变送器，低压线路阀在均衡阀打开时关闭。 这使得两个压力线之间的压力相等，使得来自换能器的任何信号对应于零压力差值。
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5.发明授权
公开(公告)号：US4607247A
公开(公告)日：1986-08-19
申请号：US764917
申请日：1985-08-12
摘要： A serial communication interface establishes communication between the microprocessor of a transmitter, to a current loop powered by a power supply. The microprocessor outputs an analog signal corresponding to a process variable and also outputs a serial communication voltage pulse signal. The analog signal is applied to a current regulating circuit which draws current from the power supply onto the current loop in an amount proportional to the process variable. A comparator has one input connected to the microprocessor for receiving the serial communication voltage pulse signal and another input for receiving a fixed selected voltage. The output of the comparator is connected to an input of the current regulating circuit in such a way so that a signal from the comparator is summed with the analog signal. The output signal of the comparator is modulated in synchronism with the voltage pulses and represents a fraction of the analog signal so that both signals can be supplied to the current loop simultaneously.
摘要翻译： 串行通信接口在发射机的微处理器之间建立与电源供电的电流环路之间的通信。 微处理器输出与过程变量对应的模拟信号，并输出串行通信电压脉冲信号。 模拟信号被施加到电流调节电路，该电流调节电路以与过程变量成比例的量将电流从电源吸取到电流回路上。 比较器具有连接到微处理器的一个输入端，用于接收串行通信电压脉冲信号，另一个输入用于接收固定的选定电压。 比较器的输出以这样的方式连接到电流调节电路的输入端，使得来自比较器的信号与模拟信号相加。 比较器的输出信号与电压脉冲同步地被调制，并且表示模拟信号的一部分，使得两个信号可以同时被提供给电流环路。
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公开(公告)号：US4604566A
公开(公告)日：1986-08-05
申请号：US763486
申请日：1985-08-07
CPC分类号： G08C19/02
摘要： A current regulating convertor includes a pulse generator which generates a voltage pulse train having a variable duty cycle. A low pass filter is connected to receive the pulse train and has a cutoff frequency which is well below the frequency of the pulse train. The low pass filter generates a D/C voltage signal which has a voltage level that is proportional to the duty cycle of the pulse train. The D/C signal is used in a circuit that draws a current from a power supply which is proportional to the voltage level of the D/C signal. The power supply is connected to the circuit by a 4-20 mA currrent loop. 6
摘要翻译： 电流调节转换器包括产生具有可变占空比的电压脉冲串的脉冲发生器。 连接低通滤波器以接收脉冲串并具有远低于脉冲串频率的截止频率。 低通滤波器产生具有与脉冲串的占空比成比例的电压电平的D / C电压信号。 D / C信号用于从与D / C信号的电压电平成正比的电源中抽取电流的电路。 电源通过4-20 mA电流回路连接到电路。
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