Multi-unit communicating system

• US 4,802,115 A
• Filed: 05/17/1985
• Issued: 01/31/1989
• Est. Priority Date: 05/17/1985
• Status: Expired due to Fees

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Ginn, Peter L.
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): CHUN, DEBRA
• Application Number:
  US06/734,995
• Time in Patent Office: 1,355 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 364/551, 364/481, 364/500
• US Class Current: 710/69
• CPC Class Codes: B01D 3/42 Regulation; Control
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: G05D 23/1905 associated with tele control
• CPC Class Codes: G08C 15/00 Arrangements characterised by the use of multiplexing for the transmission of a plurality of signals over a common path
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles

Abstract

A multi-unit data-collecting/information-generating/instruction-passing/communication-network being a multiplicity of individual microprocessor systems capable of data-collection/presenatation/order-passing associated with instrumentation, process control elements and/or information displays, indicators and recorders on a two or three wire network programmed in a manner to enable

(1) each individual information generating system comprised of one data measuring instrument generating a signal connected in juxta-position to an A/D and a microprocessor capable of converting analog signals from the instrumentation to digital signals then to serial digital strings and through a transceiver (T/R) transmit said digital serial strings onto the network,

(2) each individual information-passing system comprised of a T/R-microprocessor-A/D juxta-positioned with a process control element, said system capable of recognizing an identifier code within a serial digital string containing instructions for said process control element associated with the system to cause said element to come to computer process control designated position said system tied into the network at said element site, and

(3) each data-collecting system capable of receiving and converting selectively through T/R-microprocessor-A/D configuration an identifier code within a serial digital strings from said network, each microprocessor configuration capable of either developing process control element orders as information-passing strings, and transmitting them or providing readouts, visual displays, calculated process parameter changes, selected data storage, selected data printouts, and the like, all on a selective need to know basis at individual data-collecting sites remote from the instrumentation and control element sites.

Claims

1. A process control system which comprises

(a) a two or three wire network having connected thereto

(b) a plurality of process control elements, each associated with and in juxta-position with

(c) a position altering element capable of receiving and responding to an analog signal from an associated juxta-positioned D/A, which position altering element moves the process control element, said D/A is further associated with

(d) a juxta-positioned microprocessor associated with

(e) a juxta-positioned transceiver (T/R) said transceiver (T/R) connected to the network,

said microprocessor capable of recognizing an identifier within a serial digital string for a code that would identify the particular process control element with which the microprocessor is associated

(f) a plurality of instruments including element position indicators each capable of measuring a process variable or process control element position each generating an analog signal and each associated with an having in juxta-position therewith an analog to digital converter (A/D) for converting said instrument analog signal into a digital signal value,

(g) a separate pre-programmed microprocessor associated with each A/D for conversion into engineering notation of the said digital signal and for inclusion of at least an identification code for said measuring instrument or process control element

(h) a transceiver (T/R) associated with each said microprocessor and connected to said network for conversion of said engineering notation and associated identification code into a serial digital string for transmission onto the network, said microprocessor transceiver combination also capable of recognizing the identifiers of other microprocessor transceiver combinations on said network thus enabling it to transmit its serial digital string in proper sequence onto the network, each instrument microprocessor-transceiver combination transmitting its identification/engineering notation as a serial digital string in an ordered sequence derived from the identification itself, said network also including

(i) a plurality of microprocessors capable of performing at least one of the tasks of storing, visual readout, calculating process parameters from the received signals from selected instruments and/or ordering changes to said process control elements anyone or all of which microprocessors are remote from said instrumentation and/or said process control elements.

2. The process control system of claim 1 in which said analog value transmitted by an instrument, converted to digital value, received by a microprocessor or microprocessors on site of said instrument is processed by said microprocessor which is programmed to

store such signal and/or

compare such signal with a norm or with previous stored signal or signals, and/or

develop one or more of an average, change from last, deviation, direction, debounced value, and/or median, with or without a time frame and

communicate such pre-programmed computation or computations to the network, via said T/R.

3. In a process for controlling a system being a two or three wire network having connected thereto

a plurality of process control elements, each associated with a position altering element capable of responding to an analog signal converted from a digital signal juxta-positioned digital/analog converter (D/A) associated with each element which D/A is associated with a juxta-positioned microprocessor and a transceiver (T/R) connected to the network, the combination capable of recognizing a serial digital signal code identified for the element with which they are associated

a plurality of information-generating instruments, including element position indicators, each capable of measuring a process variable or process control element position and generating an analog signal,

a plurality of combinations associated and juxta-positioned to each such information-generating instrument consisting of

an analog to digital converter (A/D) associated with each such instrument for converting said instrument analog signal into a digital signal value,

a separate microprocessor associated with each A/D programmed to at least convert into engineering notation said digital signal and include an identification code for said measuring instrument

a T/R port associated with each said microprocessor for conversion and transmission of said engineering notation and identification code generated within said microprocessor into a serial digital string for transmission onto the network,

and a plurality of data-collecting microprocessors capable of performing at least one of the tasks of storing, visual readout, printing, calculating process parameters from the received signals from selected instruments and/or ordering changes to said process control elements, which process comprises

generating an analog signal within each process variable measuring instrument;

converting each said analog signal into a digital signal value in said juxta-positioned A/D associated with said instrument,

inputting said digital value into the microprocessor associated with said A/D, which microprocessor is programmed to at least

(1) add an identifier code identifying said instrument and said value of said measurement;

(2) develop a significant result not attainable by the single measurement alone;

(3) broadcast in sequence said identity code/result from the associated T/R port of said microprocessor as a serial digital string at an assigned time prompted by the identification code, onto the three wire network,

receiving at any data-collecting site with access to the network, remote or in close proximity, serial digital strings therefrom selected by said receiving station according to those identifications of interest which microprocessor is programmed to perform a designated task, and

transmitting onto said network from at least one of said data-collecting site(s) serial digital strings identifiable as process control element instructions, thereby to adjust said process control elements to maintain the process under control.