Method and system for displaying digital data with zoom capability

• US 5,757,357 A
• Filed: 06/30/1994
• Issued: 05/26/1998
• Est. Priority Date: 06/30/1994
• Status: Expired due to Fees

• Current Assignee: Siemens Energy & Automation Incorporated (Siemens AG)
• Original Assignee: Moore Products Co. (Siemens AG)
• Inventors: Maisenhelder, Howard III, Grande, Mark J.
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/268,497
• Time in Patent Office: 1,426 Days
• Field of Search: 345/134, 345/127, 345/131, 73/866.3, 324/113, 324/121 R, 324/379, 324/394, 364/237.7, 364/921.8, 364/178, 364/179, 364/182, 364/188, 364/189, 364/413.05, 364/413.06, 364/550
• US Class Current: 345/440.1
• CPC Class Codes: G01R 13/345 for displaying sampled signals by using digital processors by intermediate A.D. and D.A. convertors (control circuits for CRT indicators)
• CPC Class Codes: G01R 19/25 using digital measurement techniques

Abstract

A system and method for process instrumentation and control equipment. The system including a paperless, microprocessor-based, panelboard recorder having built-in data acquisition functions, a mechanism for archiving data, and a variety of display types. Memory space is conserved by deriving quantized data comprising signal samples received at a first rate and storing them for a first relatively short period in a fine quantized memory, and storing in a coarse memory, for a longer period of time, a subset of said signal samples recurring at a rate lower than the first set and having fewer quantized levels than the first set of samples. The operator can then determine whether coarse data obtained over a relatively long period or fine data obtained over a shorter period are displayed.

Claims

1. A digital strip chart recorder comprising:

an analog-to-digital converter for converting analog signals representing process variables to digital signals,

a signal conditioner electrically connected to said analog-to-digital converter for conditioning said digital signals, said signal conditioner comprising,

(i) a quantizer electrically connected to said analog-to-digital converter, said quantizer receiving and quantizing said digital signals into 12-bit words, each of said 12-bit words being stored for a first time period in a first memory electrically connected to said signal conditioner,

(ii) a divider electrically connected to said quantizer, said divider reducing said 12-bit words into 8-bit words, and

(iv) a maximum and minimum detector for detecting the maximum and minimum value of said 8-bit words, said maximum and minimum value of said 8-bit words being stored for a second time period in a second memory electrically connected to said signal conditioner, said second time period having a duration greater than said first time period,

a display for displaying said 12-bit and 8-bit data words as a function of said first and second time periods, and

a data processor electrically connected to said display and to said first and second memory, said data processor controlling said display and said first and second memory to produce a display of said 12-bit and 8-bit data words stored in said first and second memory according to an operator'"'"'s command.

2. A digital strip chart recorder comprising:

an analog-to-digital converter for converting process variables to digital signals,

a signal conditioner electrically connected to said analog-to-digital converter for conditioning said digital signals, said signal conditioner comprising,

(i) a quantizer electrically connected to said analog-to-digital converter, said quantizer receiving and quantizing said digital signals into first binary words having a first number of bits, each of said first binary words being stored for a first time period in a first memory electrically connected to said signal conditioner,

(ii) a divider electrically connected to said quantizer, said divider reducing said first binary words into second binary words having a second number of bits, and

(iii) a maximum and minimum detector for detecting the maximum and minimum value of said second binary words, said maximum and minimum value of said second binary words being stored for a second time period in a second memory electrically connected to said signal conditioner, said second time period having a duration greater than said first time period,

a display for displaying said first and second binary words as a function of said first and second time periods, and

a data processor electrically connected to said display, to said first memory and to said second memory,

wherein said data processor controls said display, said first memory, and said second memory to produce a display of said first and second binary words stored in said first and second memory according to an operator'"'"'s command.

3. The digital strip chart recorder of claim 2, wherein said first binary words have a greater number of bits than said second binary words.

4. A method for sampling, storing, and displaying process variables by means of a digital strip chart recorder, said method comprising the steps of:

converting, by means of an analog-to-digital converter, process variables from analog to digital signals, said process variables being sampled at a first sampling rate,

signal conditioning, by means of a signal conditioner electrically connected to said analog-to-digital converter, said digital signals, wherein said signal conditioning comprises the steps of,

(i) quantizing, by means of a quantizer electrically connected to said analog-to-digital converter, said quantizer receiving and quantizing said digital signals into 12-bit words, each of said 12-bit words being stored for a first time period in a first memory electrically connected to said signal conditioner,

(ii) dividing, by means of a divider electrically connected to said quantizer, said divider reducing said 12-bit words into 8-bit words, and

(iii) detecting a maximum and minimum value, by means of a maximum and minimum detector for detecting the maximum and minimum value of said 8-bit words, said maximum and minimum value of said 8-bit words being stored for a second time period in a second memory electrically connected to said signal conditioner, said second time period having a duration greater than said first time period,

displaying, by means of a display, said 12-bit and 8-bit data words as a function of said first and second time periods, and

controlling, by means of a data processor electrically connected to said display and said first and second memory, said data processor controlling said display, said first memory, and said second memory to produce a display of said 12-bit and 8-bit data words stored in said first and second memory according to an operator'"'"'s command.