JPH0440382A - Detecting system for drop of battery voltage - Google Patents

Abstract

PURPOSE:To enable accurate detection of the remaining life time of a battery by obtaining the difference between the initial time of the lowering of battery voltage which is detected by a realtime clock circuit provided with the battery as the power source and the present time. CONSTITUTION:Since the battery 15 is provided as a power source for the raltime clock circuit 16, detection circuit 19 for the drop of voltage, and register 17, the voltage of battery 15 is always monitored by the circuit 19 even if a main power source is disconnected. When the drop of voltage is detected by the circuit 19, the detected time of the drop of voltage by the circuit 16 is stored in the register 17 by the rise of detection signal. Next, when the detection of the drop of voltage made by the circuit 19 is recognized by the CPU 11 through an input port 20, the stored 17 detection time for the drop of voltage is read out from an input port 18 and the present time is read out from the circuit 16, then the remaining life time of battery 15 at the present time can be exactly detected by means of subtracting the elapsed time upto the present time through the drop time of voltage from the reference value for remaining life time of battery 15 which is being stored in a CMOS memory 14.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a battery voltage drop detection method for a backup battery of a non-volatile memory used in a control device such as a numerical control device, and in particular to a method for detecting a battery voltage drop for a backup battery of a non-volatile memory used in a control device such as a numerical control device. Regarding voltage drop detection method.

[Conventional technology]

Conventional numerical control devices are equipped with a CMOS memory backed up by a battery, and are configured so that the contents stored in the memory are not lost even if the main power is turned off.

However, since batteries have a limited lifespan, it is necessary to replace the batteries before the end of their lifespan. Therefore, conventional numerical control devices detect when the battery voltage falls below a certain value and notify the operator as a battery alarm.
I was urged to replace the battery. This battery alarm allows the operator to know when it is time to replace the battery.

[Problem to be solved by the invention]

However, in conventional circuits, a processor detects a drop in battery voltage and notifies an operator as a battery alarm. Therefore, when the main power supply is turned off, the processor does not operate, making it impossible to detect a drop in battery voltage.

FIG. 3 is a diagram showing voltage characteristics with respect to battery time. In the figure, the vertical axis indicates battery voltage, and the horizontal axis indicates time. A battery for backup of non-volatile memory such as CMOS memory is used with a constant load, and the voltage is a constant value (
For example, when the battery life becomes less than 3.5■, it is determined that the battery life is almost exhausted and it is time to replace the battery.

In the figure, this constant value voltage is indicated by ■l on the vertical axis of the battery voltage. Also, the memory retention limit voltage is the limit voltage that the battery can use, and the vertical axis of the battery voltage is V2.
It is shown by . Normally, the initial voltage of the battery is 4.5V,
The memory retention limit voltage v2 that can retain the contents stored in the nonvolatile memory is about 2V.

Here, the main power of the numerical control device is cut off at time T1,
It is assumed that the main power is turned on at time T3. The numerical control device has been stopped with the main power turned off since time T1, and even if the battery voltage falls below a certain value Vl at time T2, the processor cannot know that the battery voltage has dropped. The processor can detect a battery voltage drop at time T3 when the main power is turned on. From the processor's perspective, it is impossible to know when the battery voltage has fallen below a certain value V1. Here, the time from time T2 at which the battery voltage becomes less than a certain value (1) to time T4 at which the memory retention limit voltage V2 becomes the remaining life time that the battery can be used is defined as the remaining life time that the battery can be used. Even if the processor knows at time T3 that the battery voltage is below the constant value V1, the battery remaining life time from time T3 when the battery voltage becomes below the constant value V1 to time T4 when the memory retention limit voltage ■2 becomes It is impossible to predict accurately.

The present invention has been made in view of these points, and it stores the voltage drop detection time, calculates the difference from the current time, and calculates the remaining battery life at the current time from the standard remaining life of the battery. An object of the present invention is to provide a battery voltage drop detection method that calculates the battery voltage drop.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a battery voltage drop detection method for a backup battery of a non-volatile memory used in a numerical control device, which includes a real-time clock circuit backed up by the battery and measuring the current time; a voltage drop detection circuit that is backed up by a battery and detects a battery voltage drop in which the battery voltage becomes below a certain value; a register that is backed up by the battery and stores a voltage drop detection time at which a battery voltage drop is first detected; A batch IJ i pressure drop detection method is provided, comprising a battery remaining life time calculation means for calculating the remaining life time of the battery from the current time based on the difference between the drop detection time and the current time.

[Effect]

A voltage drop detection circuit using a battery as a power source detects a battery voltage drop in which the battery voltage falls below a certain value.

The real time clock circuit that uses a battery as a power source is
The first time when the battery voltage drop is detected is transferred to the register as the voltage drop detection time.

A register powered by a battery records the voltage drop detection time transferred from the real-time clock circuit.

When the main power is turned on, the processor of the numerical control device
When the battery voltage drop is detected from the voltage drop detection circuit,
Read the voltage drop detection time stored in the register. Next, the current time is read from the real-time clock circuit.

The processor can calculate the current remaining life time of the battery by subtracting the difference between the voltage drop detection time and the current time from the standard value of the remaining battery life time.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram of the hardware configuration of a numerical control device for implementing the present invention. The CPU II is a numerical control device l according to the system program stored in the ROM12.
O Control the entire system. The ROM 12 is an EPROM or an EEPROM. The RAM 13 is an SRAM or the like, and stores various data or input/output signals. The CMOS memory 14 is a non-volatile memory, backed up by a battery 15, and stores system parameters to be retained even after the power is turned off, a nitrogen program, an offset amount, a battery voltage drop detection value, remaining life time depending on the type of battery, and the like.

The real-time clock (RTC) circuit 16 is composed of a crystal oscillation circuit and a frequency dividing circuit for counting year, month, day, hour, minute, and second, and is backed up by a battery 15, like a general digital clock. The CPU 1 can read the output data and have a calendar function. Further, the voltage drop detection circuit 19 is backed up by a battery 15, and detects a voltage drop when the voltage of the battery 15 becomes lower than the voltage v1 shown in FIG. 3. Also,
Voltage drop detection circuit 19 is connected to input port 20 . The output data of the year, month, date, hour, minute, and second of the real-time clock circuit 16 is given to a register 17 backed up by a battery 15, and the output data of the register 17 is backed up by a battery 15.
7 is stored.

The contents of register 17 are connected to input port 18 for sensing by CPU II.

The serial port 21 outputs data and is connected to an external storage device (not shown) such as a paper tape or disk. The display control circuit 22 converts the digital signal into a display signal and supplies it to the display 26. The display 26 is a CRT or liquid crystal display device, and displays the position of each axis, the status of input/output signals, parameters, battery alarm messages, etc.

The keyboard interface 23 receives data from the keyboard 27 and passes it to the processor 11.

The digital l1024 sends and receives input/output signals to and from the machine side. The servo control circuit 25 outputs a speed command for controlling the motor 28. These components are coupled together by a system bus 29.

The voltage drop detection circuit 19 constantly monitors the voltage drop of the battery 15. When the voltage drop detection circuit 19 detects a voltage drop in the battery 15, the rise of the voltage drop detection signal causes the real-time clock circuit 16 to output the register 1.
The voltage drop detection time transferred to the register 17 is stored in the register 17.

The CPU II checks the voltage drop detection circuit 19 via the input port 20 to see if the voltage of the battery 15 is below a certain value.

Real-time clock circuit 16, voltage drop detection circuit 19
The power supply for the register 17 is backed up by the battery 15. Therefore, even if the main power supply is off, the voltage of the battery 15 is always monitored by the voltage drop detection circuit 19. When it is detected that the voltage of the battery 15 is below a certain value, the date and time at that time are transferred from the real-time clock circuit 16 to the register 17 and stored as the voltage drop detection time.

CPU II can only operate when the main power is turned on. When the main power is turned on and the CPU II reads the input port 20 and detects that the voltage of the battery 15 is below a certain value, it reads the human power port 18 and determines the year when the voltage drop was first detected as the voltage drop detection time. Know the time of the month and day.

On the other hand, the current time can be known by directly reading the real-time clock circuit 16. Therefore, by calculating the difference between the current time and the voltage drop detection time stored in the register 17, it can be determined how much time has passed since the battery voltage drop was actually detected. By subtracting this time from the standard value of the remaining life time of the battery, the current remaining life time of the battery can be calculated.

FIG. 2 is a flowchart for calculating remaining battery life in an embodiment of the present invention. In the figure, the number following S indicates the step number.

[311 CPU 1 checks whether the voltage drop detection circuit 19 detects a voltage drop of the battery 15 via the input port 20, and if a voltage drop is detected, proceeds to S2;
No processing is performed if it is not detected.

[32) The CPU 1 reads the voltage drop detection time stored in the register 17 from the manual port 18.

[S3] CPUI 1 is real-time clock circuit 16
Read the current time from.

[S4] Calculate the current remaining life time of the battery by subtracting the elapsed time from the voltage drop detection time to the current time from the standard value of the battery remaining life time.

In the above explanation, we have explained the configuration and means for calculating the remaining life time of the battery, but the calculated remaining life time of the battery should be included in the battery alarm and displayed on the display as accurate information for battery replacement. Can be configured.

〔Effect of the invention〕

As explained above, the present invention includes a real-time clock circuit backed up by a battery, a voltage drop detection circuit, and a register that stores the voltage drop detection time.
Even when the main power is off, the battery voltage drop time can be recorded and the remaining battery life can be accurately determined.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the hardware configuration of a numerical control device for implementing the present invention, Fig. 2 is a flowchart for calculating remaining battery life in an embodiment of the present invention, and Fig. 3 is a voltage characteristic of the battery with respect to time. FIG. Numerical control device CPU OM AM CMOS memory battery TC Register input port Voltage drop detection circuit input port Serial port Display control circuit Keyboard interface Digital I10 RT Keyboard system bus Patent applicant Fanuc Corporation Agent Patent attorney Takeshi Hattori

Claims (2)

[Claims] (1) A battery voltage drop detection method for a backup battery of a non-volatile memory used in a numerical control device includes: a real-time clock circuit backed up by the battery to measure the current time; and a real-time clock circuit backed up by the battery to measure the current time. a voltage drop detection circuit that detects a battery voltage drop below a certain value; a register that stores a voltage drop detection time when a battery voltage drop backed up by the battery is first detected; A battery voltage drop detection method comprising: a battery remaining life time calculation means for calculating the remaining life time of the battery from the current time based on the difference. (2) The battery voltage drop detection method according to claim 1, wherein the battery remaining life time calculating means is configured to display a battery alarm including the remaining life time of the battery on a display.