JPH0933300A - Monitor signal output apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the judgment to the normality or abnormality of a memory data of a device. SOLUTION: Data to be monitored of a memory 26 of a device are read out every specified sampling time by a data reading section 30. A data judging/ collating section 32 collates the data read out with a criterion value of a criterion data setting section 33 and outputs an increment signal when the data is normal or a decrement signal when it is abnormal. A adding/subtracting counter 34 has upper and lower limit values and adds one by the increment signal within the range or subtracts one by the decrement signal. A D/A data converting section 35 converts counts of the adding/subtracting counter 34 pertaining to data assigned by a reading data assigning section 28 into an analog voltage within a range of an upper limit voltage corresponding to the upper limit value and within the range of a lower limit voltage corresponding to the lower limit value and the results are outputted to a D/A port 36. The voltage of the D/A port 36 is detected by a tester or the like to judge the normality and abnormality of the data monitored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor signal output device for monitoring data stored in a memory in an operating state of equipment.

[0002]

2. Description of the Related Art A device status display device for monitoring and displaying data stored in a memory of an operating condition of a device is disclosed in Japanese Patent Laid-Open No. 3-27.
It is disclosed in Japanese Patent No. 1621. This device reads the stored data of a memory RAM (Random Access Memory), which is taken in by the control operation of the sequence control unit of the device, from the microcomputer side of the device to the state display device side by an address command, and provides this to the state display device. LED
The display means is used to distinguish between normal and abnormal display.

[0003]

However, in the above-mentioned conventional device, the microcomputer side of the equipment reads the state display device side to the state display device side in the signal state of the microcomputer treatment form, and associates the read data with the one-to-one correspondence. Since it is displayed on an LED or the like, it is necessary to provide a large number of display means such as LEDs corresponding to the number of data to be monitored, which causes a problem that the device configuration becomes complicated.

Further, since the data read from the device side is taken out as a signal of a microcomputer processing form, even if a general-purpose tester or oscilloscope is connected to the signal output port of the microcomputer side, the signal output from the signal output port is Since it is a digital signal, these testers and oscilloscopes cannot judge whether the read data is normal data or abnormal data, and there is an inconvenience that a dedicated status display device must be prepared.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a tester, an oscilloscope, etc. from the signal output port side of the microcomputer of the equipment without preparing a dedicated status display device. It is an object of the present invention to provide a monitor signal output device capable of easily inspecting monitor data for normality and abnormality by using the general purpose inspection means.

[0006]

In order to achieve the above object, the present invention is constructed as follows. That is, according to the present invention, in a monitor signal output device for reading and outputting data in a memory that stores data in an operating state, a data reading unit for reading each data to be monitored from the memory at a set sampling time interval, and a monitor. The judgment data setting unit that gives a judgment value for each target data and the judgment value corresponding to the data read by the data reading unit are collated. If the read data is normal, an increment signal is output. When the value is abnormal, the data judgment collating unit outputs a decrement signal respectively, and when the upper limit value and the lower limit value are set in advance and the increment signal is received within the range of the upper limit value and the lower limit value, the unit numerical value is added and the decrement is performed. When a signal is received, the addition / subtraction counter that subtracts the unit value and the reading that specifies the data to be monitored The output data designating unit, the upper limit voltage corresponding to the upper limit value of the addition / subtraction counter and the lower limit voltage corresponding to the lower limit value of the addition / subtraction counter are set, and the counter value of the addition / subtraction counter for the data designated by the read data designation unit is set to the upper limit. And a D / A data conversion unit that converts the voltage into an analog voltage within the range of the lower limit voltage and outputs the analog voltage to the D / A port on the output side.

In the present invention having the above-described structure, the data to be monitored stored in the memory is read by the data reading section at each set sampling time and added to the data judgment collating section.

The data judgment collating unit compares the read data with the corresponding judgment value given to the judgment data setting unit, and if the read data is normal, an increment signal is given and the read data is When there is an abnormality, the decrement signal is added to each addition / subtraction counter. That is, the data determination collating unit collates the read data read at the set sampling time interval with the determination value,
An increment or decrement signal is output to the addition / subtraction counter at sampling time intervals.

The addition / subtraction counter increments the counter value by a unit numerical value (for example, 1) when it receives an increment signal, and subtracts the counter value by a unit numerical value when it receives a decrement signal. The D / A data conversion unit, when the read data is designated by the read data designation unit,
As a result of converting the counter value of the addition / subtraction counter for the designated data into a voltage within the range of the upper limit voltage corresponding to the upper limit counter value and the lower limit voltage corresponding to the lower limit counter value and outputting the voltage to the D / A port on the output side, By connecting a general-purpose tester or oscilloscope to the D / A port, the voltage corresponding to the read data is detected from the D / A port, and the abnormal voltage on the lower limit voltage side within the range of the upper limit voltage and the lower limit voltage is detected. When the voltage in the range is detected, it can be judged that the read data is abnormal, and when the detected voltage is detected as the voltage in the normal range on the upper limit voltage side,
The read data can be determined to be normal, and it is possible to determine whether the read data to be monitored is normal or abnormal by only detecting the output voltage of the D / A port.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a hot water heater as an example of a combustion device including the monitor signal output device of the present embodiment. In FIG. 1, a tool main body 2 is housed in a tool case 1. A burner 4 of a combustion surface switching type is provided below the combustion chamber 3 of the apparatus main body 2, and a combustion fan 5 for air supply and exhaust is provided below the burner 4. The box-shaped nozzle holder 6 is provided with a nozzle for jetting gas to the burner 4, and the nozzle holder 6 is provided with capacity switching valves 22a, 22b, 22c for switching the burner combustion surface (switching the burner combustion capacity). Is connected to a gas supply passage 7, and fuel gas is supplied through the passage 7. The gas supply passage 7 incorporates an original electromagnetic valve 8 for opening and closing the passage and a proportional valve 10 for controlling the amount of gas supplied to the burner 4 by the opening amount.

A passage 24 is formed between the air chamber 9 below the burner 4 and the combustion chamber 3 above the burner by piping or the like, and the passage 24 is formed from the combustion fan 5 to the burner. An air volume detection sensor 23 for detecting the air volume supplied to the air conditioner 4 is provided.

The air volume detection sensor 23 is constructed by using a hot wire type wind speed sensor, a Karman vortex type wind speed sensor, a differential pressure sensor and the like.

A hot water supply heat exchanger 11 is installed above the combustion chamber 3, and a water supply pipe 12 is provided at the inlet side of the hot water supply heat exchanger 11.
Is connected, and a hot water supply pipe 13 is provided on the outlet side of the hot water supply heat exchanger 11.
Is connected. The water supply pipe 12 is provided with an incoming water temperature sensor 14 for detecting the temperature of incoming water and a flow rate sensor 15 for detecting the flow rate of incoming water.On the hot water supply pipe 13 side, a tapping temperature sensor 16 for detecting the temperature of incoming hot water, A water amount control valve 19 to be adjusted is provided.

In the figure, 18 is an igniter electrode (ignition plug) for igniting fuel gas, 20 is a frame rod electrode for detecting the flame of the burner 4, 21 is a Hall IC or the like for detecting the rotation of the combustion fan 5. A fan rotation detection sensor, 27 is an air temperature sensor attached to the nozzle holder 6 to detect the air temperature inside the appliance, and 51 is an outside air temperature sensor.

The combustion operation of this kind of equipment is carried out by a control device 17, which is usually connected to a remote controller for setting the hot water supply temperature and displaying the set temperature. There is. The combustion device 17 is, as shown in FIG.
It has a combustion control unit 25 and a memory 26 such as a RAM or a non-volatile EEPROM or the like in which data can be freely written and erased by electric signals. The memory 26 is used for various sensors.
The detection data of 14, 15, 16, 20, 21, 23, 27, 51, etc., the combustion fan 5, various valves 8, 10, 19, 22a to 22c, the operating state of various activators such as igniters, etc. Data, data of various switches, data from remote control (set temperature, time), error code life diagnosis data, set water level or P (water level) of bathtub-Q (water amount) in the case of a multifunction machine to be described later Data and the like are fetched every moment during the operation of the combustion operation and stored. The combustion control unit 25 has a built-in sequence program, reads the data in the memory 26 according to the sequence program for combustion operation, and controls the combustion operation as follows.

First, when a hot water tap (not shown) provided on the tip side of the external hot water supply pipe connected to the hot water supply pipe 13 is opened, water enters from the water supply pipe 12, and the flow of this water is detected by the flow sensor 15. When detected, the combustion control unit 25 of the control device 17 rotates the combustion fan 5 to detect the fan rotation detection sensor.
After confirming that the fan rotation has been detected by the fan 21 and the air volume detection sensor 23 has detected the air volume, the discharge of the igniter electrode 18 is started.
Then, the main solenoid valve 8, the performance switching valves 22a to 22c, and the proportional valve 10 are opened to perform burner ignition. Frame rod electrode 20
Has detected the flame, open / close the capacity switching valves 22b and 22c according to the combustion capacity, and control the valve opening drive current of the proportional valve 10 so that the hot water temperature reaches the set temperature. In order to control (the valve opening amount of the proportional valve 10) and to supply the air corresponding to the gas supply amount, the rotation of the combustion fan 5 or the air volume control is performed.

When the hot water is used and the hot water tap is closed, the passage of water to the hot water supply heat exchanger 11 is stopped, and when the stop of the water flow is detected by the signal of the flow sensor 15, each valve 8 , 22a to 22c, 10 are closed, and after that, when a post-purge period in which exhaust of exhaust gas in the combustion chamber 3 ends is completed, the rotation of the combustion fan 5 is stopped to prepare for the next hot water discharge.

Monitor signal output device in this embodiment
37, as shown in FIG. 1, a read data designating section 28, a data reading section 30, a sampling time measuring section 31,
Data judgment collation unit 32, judgment data setting unit 33, addition / subtraction counter 34, D / A data conversion unit 35, D / A port
And 36.

The read data designating unit 28 designates the data to be monitored among the data stored in the memory 26 by instructing the storage address of the data. The read data designating unit 28 can be configured by a key input means using a keyboard, a jumper line cut, or the like, but in the present embodiment example, a dip (DIP) switch is provided on the control board of the control device 17, The data reading unit 30 is instructed to monitor the data by operating the dip switch.

The data reading unit 30 has a list of data to be monitored and data at the start of reading and timing of reading (sampling time interval) of each data to be monitored. The data is read at time intervals, and the read data is added to the data judgment collating unit 32. At the time of this data reading, the sampling time measuring unit 31 sets the sampling timing by time measurement based on the data of the sampling start of data reading and the data of the sampling interval time which the data reading unit 30 has, and the data reading unit 30 The data to be monitored in the memory 26 is read according to the sampling timing signal added from the sampling time measuring unit 31.

The data judgment collating unit 32 is a data reading unit.
The data read from 30 is used as the judgment data setting unit 33
Is checked to determine whether the read data is normal or abnormal. When the read data is normal, an increment signal is output, and when abnormal, a decrement signal is output to the addition / subtraction counter 34. Table 1 shows an example of an object for which the data is judged to be normal or abnormal.

[0022]

[Table 1]

The judgment data setting section 33 is provided with a judgment value for judging whether the read data is normal or abnormal for each read target data stored in the memory 26. As this judgment value, for example, when the data to be read is the detection value of the sensor, it is given as a value within an allowable range with respect to the normal value, and the data judgment collating unit 32 determines that the data read value is normal when the data is within the allowable range. If it is out, it is determined to be abnormal.

When the data to be read is data for turning the switch on and off, for example, a decision value such as 1 for switch on and 0 for switch off is given, and the data decision collating unit 32 reads the data. If the data matches the judgment value according to the operating state of the device, it is judged as normal, and if not, it is judged as abnormal. Further, in the data determination of the hot water supply continuous combustion limiter operation, a determination value such as 1 for hot water supply combustion and 0 for hot water supply combustion stop is given,
The data determination / collation unit 32 outputs a decrement signal (1 in this embodiment) when the read data of the frame rod electrode 20 is the hot water supply combustion data, that is, 1 data, and the read data is the hot water supply combustion stop data, that is, 0. In the case of the above data, an increment signal (24 in this embodiment) is output. In this way, the data judgment collating unit 32 collates with the judgment value of the judgment data setting unit 33, and outputs an increment signal when the read data is normal and a decrement signal when the read data is abnormal.

An upper limit value and a lower limit value are given to the addition / subtraction counter 34 in advance. In this embodiment, a numerical value of 24 is given as the upper limit value, and a numerical value of 0 is given as the lower limit value, and the addition / subtraction counter 34 receives the unit numerical value when the increment signal is added from the data judgment collation unit 32 (this embodiment In the example, 1) is added, and when a decrement signal is added from the data determination / collation unit 32, the unit value, for example, 1 is subtracted from the counter value. That is, when the read data is normal, the data determination / collation unit 32 intermittently outputs an increment signal at the sampling time interval, and the count value of the addition / subtraction counter 34 is incremented by one each time the increment signal is added. Up, and after reaching the upper limit value of 24, the upper limit value of 24 is maintained. When the read data is abnormal, a decrement signal is intermittently output at the sampling time intervals from the data determination / collation unit 32, so that the count value of the addition / subtraction counter 34 is, for example, 1 each time the decrement signal is added.
Each time the lower limit value of 0 is reached, the lower limit value of 0 is reached.
Maintain the value of.

The D / A data converter 35 reads the counter value of the addition / subtraction counter 34 corresponding to the data to be monitored specified by the read data specifying unit 28, and converts the read counter value into an analog voltage. In this embodiment, the output voltage range of the D / A port 36 is 0V to 5V.
As shown in FIG. 3, this output voltage range is converted by assigning a hexadecimal 1 byte to a decimal number and assigned, and a value of 0V to 5V is assigned to a value of 0 to 255. There is. The lower limit value 0 of the addition / subtraction counter 34 corresponds to 0V, the upper limit value 24 of the addition / subtraction counter 34 corresponds to the value of 3.3V, and the hexadecimal 1 byte is converted into a decimal value. Gives a value of 168. Thus, D
The range of the lower limit value 0 and the upper limit value 24 of the addition / subtraction counter is given to the / A data conversion unit 35 as a value of 0 to 168 by converting the hexadecimal 1 byte into a decimal value. Converted to 0V to 3.3V.

That is, the read counter value from the addition / subtraction counter 34 is converted into hexadecimal 1-byte decimal conversion data by proportional calculation, and the value is converted into an analog voltage by proportional calculation to D / A. Output to port 36. For example, when the counter value of the addition / subtraction counter is 23, the hexadecimal 1-byte decimal conversion data is 161, and the value is converted to an analog voltage of 3.16 V by proportional calculation. Similarly, when the counter value of the adder / subtractor counter 34 is 22, the hexadecimal 1-byte decimal conversion data has a value of 154, which is converted to an analog voltage of 3.025 V for D / A.
Output on port 36.

As described above, in this embodiment, as shown in FIG. 4, when the data read from the memory 26 is normal, the counter value of the addition / subtraction counter 34 is incremented by one. When the upper limit value of 24 is reached and the read data is abnormal, the counter value of the addition / subtraction counter 34 is decremented by 1 and reaches the lower limit value of 0. When the read data specifying unit 28 specifies the data to be monitored, the addition / subtraction counter 34 for the specified data is specified.
The counter value of is converted into hexadecimal 1-byte decimal conversion data, further converted into an analog voltage within the range of 0V to 3.3V, and output to the D / A port 36.

By connecting a tester or an oscilloscope to the D / A port 36, the voltage is detected, and the detected voltage is 3.3, which is the upper limit value of the counter.
If it is V, it can be judged to be normal, and if it is 0 V, it can be judged to be abnormal. In addition, in the present embodiment, when the count value of the addition / subtraction counter 34 is in the range of 5 to 24, it is determined to be normal,
In the range of 0 to 4, it is determined that there is an abnormality. Therefore, the voltage detected at the D / A port 36 is 0.6875V.
It is judged to be normal at 3.3 V, and judged to be abnormal when it is in the range of 0 V to 0.55 V, and it is judged to be normal or abnormal by the read data before the count value of the addition / subtraction counter 34 reaches the upper limit value or the lower limit value. I am able to do that. Of course, it is of course possible to judge whether the read data is normal or abnormal by confirming that the counter value of the addition / subtraction counter 34 has reached the upper limit value or the lower limit value.

FIG. 5 is a system configuration diagram schematically showing combustion equipment of a combined bath / hot water supply system. In this bath / hot water supply complex machine, a hot water supply mechanism 54 and a reheating mechanism 55 are connected via a pouring mechanism 56. The components of the hot water supply mechanism 54 that perform hot water supply combustion are configured in the same manner as the water heater shown in FIG. 2, and the reheating mechanism 55 is a circulation pump 53 incorporated in the reheating circulation path 29 connected to the bathtub 52. Driving a bath
The hot water in 52 is circulated, and when the circulated hot water passes through the reheating heat exchanger 57, it is heated by the combustion heat of a bath burner (not shown) to reheat the hot water in the bathtub.

The pouring mechanism 56 includes the hot water supply pipe 13 and the reheating circulation path 29.
There is a pouring passage 41 connecting between the pouring passage 41 and a pouring electromagnetic valve 42, a negative pressure closing valve 43, and a check valve 44. In addition, 39 is a hot water supply confirmation switch that detects the hot water supply state, 45 is a pressure sensor that detects the water level of the bathtub 52, 46 is a hopper tank, 47 is a tank drainage passage, 48 is a check valve, 49 is a tank drainage solenoid valve, and 50 is Two-way valve and 58 are bath temperature sensors, respectively.

In this type of equipment, the pouring electromagnetic valve 42 is opened as shown in FIG. 5 (a) to allow the hot water produced by the hot water supply heat exchanger 11 to pass through the pouring passage 41 and the reheating circulation passage 29. It can be dropped into the bathtub 52 for filling. Further, as shown in (b) of the figure, the two-way valve 50 is switched to the tank drain passage 47, the tank drain solenoid valve 49 is opened,
By turning on the circulation pump 53, the hopper tank 46
Hot water inside is drained to the bathtub 52 side. In this bath / hot water supply complex machine, in addition to the abnormality determination of the monitoring target data on the side of the hot water supply mechanism shown in Table 1, the abnormality determination of the monitoring target data on the bath side as shown in Table 2 is performed. Become.

[0033]

[Table 2]

In this abnormality determination on the bath side, for example, when an abnormality determination of a bathtub drain plug is made, the determination is made as follows in units of liter of pouring into the bathtub 52. The pouring amount read from the memory 26 from the start of pouring is 180/20
A decrement signal is output from the data determination / collation unit 32 every time the liter is reached, and when the count value of the addition / subtraction counter 34 reaches 0, the analog conversion voltage of the D / A data conversion unit 35 becomes 0 V, and the read data designation unit When the bathtub drain plug removal data is designated at 28, if the detection voltage of the tester applied to the D / A port 36 is 0 V, it is possible to determine the abnormality of the bathtub drain plug removal. Further, in the case of making an abnormality judgment of the continuous combustion exceeding the bath continuous combustion limiter, as in the case of the hot water supply continuous combustion limiter operation,
Every time the combustion of the bath burner is detected at every sampling,
A decrement signal is output from the data determination / collation unit 32,
When the count value of the addition / subtraction counter 34 becomes 4, it can be judged that the continuous combustion time on the bath side has reached 90 minutes or more. In addition, the normal / abnormal determination of various operating states on the bath side shown in Table 2 is performed in the same manner as in the hot water supply combustion described above.

According to the present embodiment, the signal for determining whether the monitored data is normal or abnormal is converted into an analog voltage and output to the D / A port 36. It is not necessary to prepare the status display device of, and it is possible to specify the various data to be monitored by using a general-purpose tester or oscilloscope, and it is possible to make the determination by simply detecting the voltage of the common D / A port 36. When inspecting and inspecting each data at the site where the combustion equipment is installed, the work becomes very easy, and moreover, it becomes possible to quickly and surely judge whether the data is normal or abnormal.

Moreover, a plurality of LEDs are provided in a one-to-one correspondence with each data to be monitored, as in the conventional status display device.
It is not necessary to provide display means such as
It is possible to judge whether the data is normal or abnormal simply by applying it to the / A port 36, and even an unskilled worker can easily judge whether the read data is normal or abnormal. be able to.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example,
In the above embodiment, the upper limit value of the addition / subtraction counter 34 is 24,
Although the lower limit value is set to 0, the upper limit value and the lower limit value can be appropriately changed and set, and the range of the analog voltage converted and output to the D / A port 36 can be arbitrarily set according to the specifications. .

Further, in the above-described embodiment, as the combustion equipment, a single-function water heater as shown in FIG. 2 (a water heater having only a hot water supply function) or a bath / hot water combined machine shown in FIG. 5 has been described. However, the present invention is also applied to other various combustion equipment such as a heater, an air conditioner, an air conditioner, and an air conditioner, and is also applied to home appliances, vehicles (vehicles), etc. other than the combustion equipment. Also applies.

[0039]

According to the present invention, the read data of each monitored object in the memory of the device is collated with the corresponding judgment value, and when the read data is normal, the counter value of the addition / subtraction counter is incremented by a unit value by the increment signal, When the read data is abnormal, the decrement signal subtracts the counter value of the addition / subtraction counter by a unit value, and when the data to be monitored is specified, the counter value of the addition / subtraction counter for the specified data is set to the upper limit corresponding to the upper limit of the addition / subtraction counter. Since the voltage and the analog voltage within the lower limit voltage range corresponding to the lower limit value of the addition / subtraction counter are converted and output to the D / A port on the output side, the data to be monitored can be specified and D By simply connecting the voltage detection end of a general-purpose tester or oscilloscope to the / A port, / It becomes possible to detect the analog voltage of the A port, a result, ease of normal and abnormal judgment of the read data, and it is possible to perform accurately.

As described above, according to the present invention, it is not necessary to prepare a dedicated status display device as in the conventional example, data to be monitored is designated, and a general-purpose tester or the like is simply applied to the D / A port. It is possible to judge whether the data is normal or abnormal, and it is very convenient to check or inspect the data stored in the memory of the device, especially at the site where the device is installed. The judgment of normality and abnormality of
Since it is possible to make a clear judgment based on the value of the voltage taken out from the D / A port, even a worker who does not need to be skilled can easily and accurately judge whether the data is normal or abnormal.

Further, in the present invention, since the analog voltage corresponding to the normality and the abnormality of the data can be detected from the common D / A port, it corresponds to the kind of the data to be read out one by one like the state display device of the conventional example. Therefore, it is not necessary to provide a large number of display means such as LEDs, and the utility value thereof is great.

Further, according to the present invention, the data of the transient counter value before the counter value of the addition / subtraction counter reaches the upper limit or the lower limit can be found by detecting the analog voltage of the D / A port. The effect that the transitional situation can be judged is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is a system configuration diagram of a water heater equipped with the device of the present embodiment.

FIG. 3 is an explanatory diagram of a method of converting a counter value of an addition / subtraction counter into an analog voltage in the present embodiment example.

FIG. 4 is an explanatory diagram showing a change state of a counter value of an addition / subtraction counter and a conversion mode thereof into an analog voltage together with a normal / abnormal determination region of data.

FIG. 5 is a schematic system diagram of a combined bath / hot water supply system.

[Explanation of symbols]

 26 Memory 28 Read data designation unit 30 Data read unit 32 Data judgment collation unit 33 Judgment data setting unit 34 Addition / subtraction counter 35 D / A data conversion unit 36 D / A port 37 Monitor signal output device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G08B 23/00 530 G08C 15/00 D G08C 15/00 G01R 31/28 B (72) Inventor Obayashi Naoki, 3-4 Fukamidai, Yamato City, Kanagawa Prefecture, inside Gaster Co., Ltd.

Claims (1)

[Claims] 1. A monitor signal output device for reading and outputting data in a memory storing data of operating states, and a data reading section for reading each data to be monitored from a memory at a set sampling time interval, and a monitor target. When the read data is normal, the judgment data setting unit in which the judgment value is given for each of the data and the judgment value corresponding to the data read by the data reading unit are collated. In the case of an abnormality, a data judgment collating unit which outputs a decrement signal respectively, and when an upper limit value and a lower limit value are set in advance and the increment signal is received within the range of the upper limit value and the lower limit value, the unit numerical value is added and the decrement signal is added. When the counter is received, the addition / subtraction counter that subtracts the unit value and the read data that specifies the data to be monitored. Data specifying section, an upper limit voltage corresponding to the upper limit value of the addition / subtraction counter and a lower limit voltage corresponding to the lower limit value of the addition / subtraction counter are set, and the counter value of the addition / subtraction counter for the data designated by the read data designation section is set to the upper limit. A monitor signal output device having a voltage and a D / A data conversion unit for converting the voltage into an analog voltage within a range of a lower limit voltage and outputting the analog voltage to a D / A port on an output side.