JPH1079658A - Transmission terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a transmission terminal to which a plurality of detection switches are connected. SOLUTION: This transmission terminal is provided with a power supply circuit 11 to supply power to its internal sections. Furthermore, the terminal 30 is provided with a power supply circuit 31 to step down a power supply voltage applied to detection switches 2 connected to the transmission terminal 30. Thus, since the power consumption in the power circuit in each detection switch 2 is reduced, the entire power consumption is reduced in the case that the detection switches 2 are connected to the transmission terminal 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission terminal for connecting a plurality of detection switches and transmitting a serial signal.

[0002]

2. Description of the Related Art In many cases, a large number of detection switches, such as photoelectric switches and proximity switches, used in a production line, a transfer line, etc. are used at the same time. Reportedly. For this reason, when each of them is independently connected to the control unit, there is a disadvantage that the number of wirings is increased and erroneous wirings are also increased. Therefore, a plurality of detection switches are temporarily connected to a transmission terminal for connection of the detection switch, and serial transmission is performed between the transmission terminal and the control unit using a single cable, so that the number of wirings and the wiring space of the entire system are reduced. A transmission terminal that reduces the number of transmissions is used.

FIGS. 3A and 3B are views showing the appearance of a transmission terminal. In FIG. 3A, connectors 3 a to 3 d to which four detection switches 2 can be connected are provided in the connector part of the transmission terminal 1. A terminal block 4 for transmitting a serial signal is also provided in the transmission terminal. FIG. 3B is an external view showing a transmission terminal in which a larger number of detection switches can be connected simultaneously. FIG. 4 is a block diagram showing the structure of this transmission terminal. The transmission terminal is, for example, DC as the power supply voltage.
24 V is supplied, and each block in the transmission terminal 1 includes a power supply circuit 11 that supplies power by stepping down to 5 V, for example, and a detection switch signal input circuit 12 that receives a signal from the detection switch 2. . The detection switch signal input circuit 12 supplies a parallel signal from each detection switch 2 to the transmission control circuit 13. The transmission control circuit 13 converts a parallel signal into a serial signal and transmits the signal to a control unit such as a programmable controller (not shown) via a transmission signal output circuit 14. A signal from the control unit is input to the transmission control circuit 13 via the transmission signal input circuit 15. The operating state of the transmission terminal 1 is displayed on a status indicator 16 and an address setting switch 17 for setting an address unique to the transmission terminal is provided.

Next, an example of a circuit of each detection switch is shown in FIG. Each detection switch has a power supply voltage of 24 as shown in FIG.
There is a power supply circuit 21 for converting V to a use voltage in the detection switch, for example, 5 V, and this power is supplied to each unit. The output of the detection circuit 22 is connected to a signal processing circuit 23, and the output transistor 24 is driven as a switch signal. The output transistor 24 has an open collector output, and is connected to the detection switch signal input circuit 12.

[0005]

However, in such a transmission terminal, the loss of the power supply inherent to the transmission terminal and the loss of each detection switch are added, and a large number of detection switches are connected in close proximity to a narrow space. Therefore, there is a disadvantage that the temperature rise is large. For example, FIGS. 4 and 5
In the example, the voltage output from the power supply circuit 11 in the transmission terminal 1 is 5 V, the output current is 40 mA, the circuit efficiency η of the power supply circuit is 0.8, and the power consumption in the power supply circuit is P. _reg , input power P _IN , output power P _OUT
Then, the following equation is established. P _reg = P _IN -P _OUT P _IN = P _OUT / η P _reg = P _OUT (1 / η-1) = 0.2 (1 / 0.8-1) = 0.05 W Is 5V × 40mA = 0.2W, and the loss of the transmission terminal 1 is 0.25W.

The loss in the detection switch 2 is caused by the power supply circuit 21
Is used to reduce the voltage of 24 V to 5 V. If the output current is 50 mA, the loss of the power supply circuit is expressed by the following equation. P _reg = I (V _IN −V _OUT ) = 50 mA × 19 V = 0.95 W Assuming that the internal circuit loss is P _L , P _L = 5 V × 50 mA = 0.25 W. Therefore, the loss of the entire detection switch is P = P _reg + P _L = 0.95 + 0.25 = 1.2 W. Therefore, the total power loss including the four detection switches 2 and the transmission terminal is expressed by the following equation. P _total = 0.25 + (1.2 × 4) = 5.05 W However, in such a conventional transmission terminal, since a large number of detection switches are closely attached to the transmission terminal, a heat radiation effect cannot be expected, and There was a drawback that it would be. Further, there is a disadvantage that usable components are limited because the temperature of electronic components rises greatly.

The present invention has been made in view of such a problem of the conventional transmission terminal, and has as its object to reduce power consumption at the transmission terminal.

[0008]

According to the present invention, a plurality of detection switches are detachably connected to supply power to the detection switches and convert switch signals obtained from the plurality of detection switches into serial signals. At the transmission terminal to transmit, step down the voltage input from outside,
A detection switch power supply circuit for supplying the detection switches to the plurality of detection switches.

According to the present invention having such features,
The power supply voltage applied from the outside is stepped down and supplied to each detection switch as a voltage slightly higher than the voltage of the detection switch. Therefore, the power consumption of the power supply circuit in each detection switch is reduced, and the power consumption of the transmission terminal can be reduced as a whole.

[0010]

FIG. 1 is a block diagram showing a configuration of a transmission terminal 30 according to this embodiment. The same parts as those in the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. In the transmission terminal 30, the power supply circuit 11 supplies power to each block in the transmission terminal, and the detection switch signal input circuit 12 receives a signal from each detection switch 2 connected to the transmission terminal 30 and performs transmission control. The signal is converted into a serial signal via the circuit 13,
The transmission signal is transmitted from the transmission signal output circuit 14 to the control unit as a serial signal. In this embodiment, in addition to the power supply circuit 11 as a power supply terminal, a detection switch power supply circuit 31 for supplying power to each detection switch 2 is provided.
Is provided. The power supply circuit 31 for the detection switch is, for example, 24 V
Is supplied to each detection switch 2 as a power supply voltage of 12 V. This transmission terminal 3
The configuration of the detection switch 2 connected to 0 is the same as that of the conventional example. As the output voltage of the power supply circuit 31, a voltage capable of ensuring a difference between a power supply voltage used in the detection switch 2, here 5V, and an input voltage necessary for the operation of the power supply circuit 21 in the detection switch is selected. Assuming that the allowable range of the input voltage is 12 to 24 V, the detection switch 2 selects the lowest voltage 12 V here.

By using such a power supply circuit 31 for the detection switch, the input voltage of the power supply circuit 21 in the detection switch 2 is reduced, so that the power consumption is also reduced and the power consumption as a whole is suppressed. be able to.

[0012]

Next, a description will be given of an embodiment in which the power consumption of each transmission terminal and the detection switch in the circuits shown in FIGS. First, the power supply circuit 11
Find the loss at If the loss is P _reg1 , the input power is P _IN , the output power is P _OUT , and the circuit efficiency is η = 0.8, P _OUT = 5 V × 40 mA = 0.2 W P _reg1 = P _IN −P _OUT P _IN = P _OUT / ηP _reg1 = P _OUT (1 / η−1) = 0.2 (1 / 0.8−1) = 0.05 W Next, the loss in the detection switch power supply circuit 31 is determined. _Assuming that the loss is P _reg2 , the input power is P _IN , the output power is P _OUT , and the circuit efficiency is η = 0.8, P _OUT = 12 V × 200 mA = 2.4 W P _reg2 = P _IN −P _OUT P _IN = P _OUT / ηP _reg2 = P _OUT (1 / η−1) = 2.4 (1 / 0.8−1) = 0.6 W

Next, losses in internal circuits other than the power supply circuits 11 and 31 are determined. Assuming that the loss is P _L , P _L = 5 V × 40 mA = 0.2 W. Therefore, the loss at the transmission terminal 30 is as follows. P = P _reg1 + P _reg2 + P _L = 0.05 + 0.6 + 0.2 = 0.85W

Next, the loss at each detection switch 2 is determined.
First, the loss in the power supply circuit 21 is expressed by the following equation. Loss P
_reg , input voltage V _IN = 12V, output voltage V _OUT = 5
V, when the load current is I = 50 mA, determine the loss in _{P reg = I (V IN -V} OUT) = 50mA × 7V = 0.35W then the internal circuits other than the current circuit 21. Loss: When P _L, the _{P L = 5V × 50mA = 0.25W} . Therefore, the loss at the detection switch is expressed by the following equation. _{P = P reg + P L =} 0.35 + 0.25 = 0.6W

Therefore, when four detection switches 2 are connected to the transmission terminal 30 of this embodiment, the total power consumption is as follows. P _total = 0.85 + (0.6 × 4) = 3.25 W By providing the power supply circuit 31 for reducing the voltage supplied to the detection switch 2 in the transmission terminal 30 as described above, the total Power consumption can be significantly reduced.

[0016]

As described in detail above, according to the present invention, the power consumption of the transmission terminal can be greatly reduced as compared with the conventional example. Therefore, the amount of heat generated by the transmission terminal is small,
Since the temperature rise is small, an excellent effect that a transmission terminal can be configured using ordinary electronic components can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a transmission terminal according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a detection switch according to the embodiment.

FIG. 3 is a perspective view illustrating an appearance of a transmission terminal.

FIG. 4 is a block diagram showing a configuration of a conventional transmission terminal.

FIG. 5 is a block diagram showing an internal configuration of a conventional detection switch.

[Explanation of symbols]

 1, 30 Transmission terminal 2 Detection switch 11, 21 Power supply circuit 12 Detection switch signal input circuit 13 Transmission control circuit 14 Transmission signal output circuit 15 Transmission output input circuit 31 Power supply circuit for detection switch

Claims (1)

[Claims] A transmission terminal for detachably connecting a plurality of detection switches, supplying power to the detection switches, converting a switch signal obtained from the plurality of detection switches into a serial signal, and transmitting the serial signal; A transmission terminal, comprising: a detection switch power supply circuit that steps down a voltage input from the power supply and supplies the voltage to the plurality of detection switches.