JP2526814B2 - Data transmission system - Google Patents

Description

The present invention relates to a data transmission system for serially transmitting a detection signal detected by a detection circuit to a receiving side circuit.

[Conventional technology]

Conventionally, as this type of detection circuit, there is a "multi-rotation absolute value encoder" (Japanese Patent Application No. 61-230253).

FIG. 7 is a configuration diagram thereof, FIG. 8 is a waveform diagram of output signals after power-on of the conventional example of FIG. 7, and FIG. 9 is a diagram showing input / output signal lines of the encoder of FIG.

This encoder detects that the encoder is powered on and transmits the multi-rotation amount of the encoder and the absolute angle within one rotation to the receiving side circuit by the rotation speed serial data and the serial data of the initial position incremental pulse. It is a directional transmission type detector.

The optical absolute encoder that detects the absolute angle within one rotation is attached to the shaft 1 and has a rotating disk 2 for detecting the absolute angle within one rotation, an LED 4 for projecting light on this, and a fixed slit. 5, a photodiode array 6 of a light receiving element, and a waveform shaping circuit 7 _{1 to} 7 ₁₅ for shaping the detection signals of these into a rectangular wave. The magnetic encoder for detecting multi-rotation includes a rotating unit. Magnet
The rotating disc 8 ₁ provided with the 8 _2, power to perform a magnetoresistive element 9 to detect the rotational speed, a waveform shaping circuit 10, the switching to the battery power supply from the outside when the power supply is lost A switching circuit 14, a large-capacity capacitor 15 that drives the circuit with stored electricity when the battery power is exhausted, a voltage detection circuit 13 that detects the power supply voltage, and a multi-rotation detection signal that counts and holds the numerical value. After the power is turned on, the control circuit 12 with a built-in microcomputer for storing the multi-rotation detection signal and the absolute value signal within one rotation are
It comprises a control circuit 17 "including a gate array for serially transmitting channel, B channel and Z channel signals respectively, and a balanced line driver circuit 16 for sending these signals to a receiving side circuit.

In this system, the signal is transmitted upon detection of power-on, so that the signal can be transmitted with a smaller number of signal lines as compared with the parallel absolute encoder.

[Problems to be Solved by the Invention]

However, this method has a drawback that the power must be turned off and then turned on again in order to confirm whether the receiving side circuit can reliably receive the encoder signal in one transmission. As shown in Fig. 10, a request signal and a data reception signal are added and the request signal changes to "H" level or "L" level as a method of obtaining a signal with the power turned on. In that case, it is possible to obtain a signal from the multi-rotation absolute value encoder, but there is a drawback that the number of signals must be increased.

An object of the present invention is to provide a data transmission system which can perform bidirectional transmission without increasing the number of signal lines.

[Means for solving the problem]

In the data transmission system of the present invention, a differential type transmission / reception circuit is used as a transmission / reception circuit for transmitting / receiving a signal between the detection circuit and the receiving side circuit, and even if the output signal is short-circuited in the transmission / reception response, it is short-circuited. After the state is released, a protection reply is provided so as to operate surely, and the detection circuit detects the signal transmitted from the reception side circuit by the signal line between the reception side circuit and the detection circuit, and It has means for transmitting a signal having a predetermined content to the receiving side circuit after a fixed time.

[Action]

In a transmission state in which the detector is not transmitting a signal (for example, a state in which the encoder is stopped), transmission is started to the detector side by the signal line between the receiving side circuit side and the detector.
On the detector side, by detecting the transmitted signal, a signal having a predetermined content is transmitted to the receiving side circuit after a lapse of a certain time.

Thereby, bidirectional transmission can be performed without increasing the number of signal lines. [Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of a data transmission system including a multi-rotation absolute value encoder of the present invention, and FIG. 2 is an output signal diagram of the bidirectional transmission detector 23 of FIG. 1 in an incremental pulse state, FIG. 3 is a waveform diagram of a signal on the receiving side circuit 24 side in the bidirectional transmission detector 23 of FIG. 1 and an output signal from the bidirectional transmission detector 23 side, and FIG. 4 is a signal in FIG. A circuit diagram of the detection circuit 18 and a detailed connection diagram with the receiving side circuit 24. FIG. 5 (1) is a signal timing diagram when the input signal a of the line driver circuit 16 is at "H" level, FIG. 2) is a signal timing chart when the input signal a of the line driver circuit 16 is at "L" level.

The data transmission system of the present embodiment is the output of the balanced line driver circuit 16 (differential transmission / reception circuit) of the Z and channel of the multi-rotation absolute value encoder of the conventional example shown in FIG.
Check that the signal detection circuit 18 (detection circuit) and the signal detected by the signal detection circuit 18 are not erroneous signals or noise due to a short circuit or disconnection of the signal cable. A signal determination circuit 19 for determining by comparing with a pattern determined by detection is added, and the output signal thereof is output to the control circuit 17.

As shown in FIG. 4, the signal detection circuit 18 is composed of a simple logic circuit that uses the input signal a and the output signals b and c of the Z-channel balanced line driver circuit 16 as input signals. Further, the Z-channel balanced line receiver circuit 21 on the receiving side circuit 24 side is in the receiving state when the enable signal j is at "L" level, and the balanced line driver circuit 22 is in the transmitting state when the enable signal j is at "H" level. Become.

Next, the operation of the signal detection circuit 18 is shown in FIG.
The time chart of (2) will be described.

First, when the input signal a of the line driver circuit 16 on the bidirectional transmission detector 23 side is at "H" level, the enable signal j is changed to "H" level from the receiving side circuit 24 and the signal is transmitted. This will be described with reference to FIG. The output signal b on the side of the bidirectional transmission detector 23 is at "H" level, but when the signal i goes to "L", the signal g goes to "L", so the signal b is forced to go to "L" level. . However, line driver circuit 16,2
2 has a protection circuit so that even if it is forcibly set to "L" level, the short circuit current will not flow and the circuit will not be damaged. Since the signal c is at the "L" level, even if the signal i is at the "L" level, the signal h does not go to the "H" level and remains at the "L" level. In this way, when the signal i is transmitted from the receiving side circuit 24, the same signal as the transmission signal i is received by the detector as the output signal f of the signal detection circuit 18.

Next, when the input signal a of the line driver circuit 16 on the bidirectional transmission detector 23 side is "L" level and the transmission is started from the receiving side circuit 24 side, the same as the transmission waveform of the transmission signal i is similarly obtained. The waveform will be received as the output signal f (FIG. 5 (2)).

That is, regardless of the signal level of the line driver circuit 16, a signal can be sent from the receiving side circuit 24 side to the bidirectional transmission detector 23 side using this signal line. Since the encoder of the conventional example is an incremental type encoder as shown in FIG. 2 after the power is turned on, it is not necessary to provide the signal detection circuit 18 on the Z and channel signal lines in the transmission state (the signal does not change. This is because the state is long and there is a high probability that transmission can be performed from the receiving side. When a signal encoded as ASCII (ASCII) code (for example, "R" (not shown) corresponding to a request) is transmitted from the receiving side to the detector in the transmitting state in this way, the signal detecting circuit In 18 this is detected, and in the signal judgment circuit 19 this is "R"
And sends a signal to the control circuit 17. In the control circuit 17, the current value data is changed to Z,
As shown in FIG. 3, from the channel output, the rotation speed serial data and the current position incremental pulse are sent to the receiving side circuit side. On the receiving circuit 24 side, after a certain time, for example, 10 mS
After that, the enable signal j is set to the “L” level to be in the receiving state, and the signal from the bidirectional transmission detector 23 is received. This is to determine whether the transmitted signal is noise or an error motion signal due to some cause.

With such a configuration, when the bidirectional transmission detector 23 is in the transmission state, the multi-rotation amount of the bidirectional transmission detector 23 and the absolute angle data within one rotation are always transmitted from the receiving side circuit 24 side. You can know. Of course, the current value data can be obtained from the other A and B channel signal lines as when the power is turned on, but in the present embodiment, Z and Z are used so that a complicated circuit for switching the A and B channel signals is not required. You are using a channel.

In this way, since the signal can be sent from the receiving side circuit 24 side to the bidirectional transmission detector 23 side, and further can be coded,
Various data can be exchanged in addition to the multi-rotation amount and absolute angle.

FIG. 6 is a block diagram of another embodiment of the data transmission system of the present invention.

In this embodiment, in addition to the rotation amount, a circuit 20 for detecting whether the power supply voltage or the battery voltage on the bidirectional transmission detector 23 side is normal or abnormal is added. The voltage is compared with the reference voltage by the comparator, and the output of the comparator when the battery voltage is lower than the reference voltage becomes "H" level, and the control circuit 17 'is notified. Control circuit
17 'can know whether to send the current value data or the voltage value data based on the content of the ASCII code sent from the receiving side circuit 24 side. Also for this, a circuit for transmitting voltage detection information may be added to the control circuit 17 '.

The circuit for obtaining the current value data from the A and B channel signal lines is the same as that for the Z and channel. However, it is necessary to have a circuit that determines and switches between the current value data and the incremental pulse. Further, during transmission / reception, it is necessary for the encoder to move and not emit an incremental pulse. Of course, signals can be exchanged on the A and B channels. Therefore, the present invention is not limited to Z, channels.

Also, in the claims, "from the receiving side circuit ...
"Means for detecting transmitted signal" and "by the signal ...
.. "Means for transmitting signals to the receiving circuit" are all
It is provided in the signal detection circuit 18, which is a detection circuit.

〔The invention's effect〕

As described above, the present invention is based on the detector 23 for bidirectional transmission.
Since the output signal circuit on the side has the signal detection means capable of detecting the signal sent from the receiving side circuit 24 side, there is an effect that bidirectional transmission can be performed without increasing the number of signal lines. is there.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the data transmission system of the present invention, FIG. 2 is an output signal diagram in the incremental pulse state of the bidirectional transmission detector 23 of FIG. 1, and FIG.
FIG. 4 is a waveform diagram of the signal on the receiving side circuit 24 side in the bidirectional transmission detector 23 and the output signal from the bidirectional transmission detector 23 side, and FIG. 4 is a circuit diagram of the signal detection circuit 18 in FIG. And a detailed connection diagram with the receiving side circuit 24, FIG. 5 (1) is a signal timing diagram when the input signal a of the line driver circuit 16 is at “H” level, and FIG. 5 (2) is a line driver circuit. FIG. 6 is a timing chart of signals when 16 input signals a are at “L” level, FIG. 6 is a configuration diagram of another embodiment of the data transmission system of the present invention, and FIG. 7 is a conventional multi-rotation absolute value encoder. FIG. 8 is an output waveform diagram of the conventional multi-rotation absolute value encoder of FIG. 7 after power-on, and FIG. 9 is input / output of the conventional multi-rotation absolute value encoder of FIG. Figure 10 shows the number of signal lines, and Fig. 10 shows a multi-rotation absolute value encoder with the addition of request signal and data reception signal lines. Is a diagram illustrating an example of da. 1 ... Shaft, 2 ... Rotating disk, 4 ... LED, 5 ... Fixed slit, 6 ... Photodiode array, 7 _{1 to} 7 ₁₅ ... Waveform shaping circuit, 8 ₁ ... Rotating disk, 8 ₂ ... … Magnet, 9… Magnetoresistive element, 10… Waveform shaping circuit, 12, 17, 17 ′… Control circuit, 13… Voltage detection circuit, 14… Power supply switching circuit, 15… Large-capacity capacitor, 16 ...... Balanced line driver circuit, 18 …… Signal detection circuit, 19 …… Signal judgment circuit, 20 …… Power supply, battery power abnormality detection circuit, 21 …… Balanced line receiver circuit, 22 …… Balanced line driver circuit . 23 …… Bidirectional transmission detector (multi-turn absolute encoder) 24 …… Receiving side circuit

Claims (1)

(57) [Claims] 1. A data transmission system for serially transmitting a detection signal detected by a detection circuit to a reception side circuit, wherein a differential type transmission / reception circuit is used as a transmission / reception circuit for transmitting and receiving a signal between the detection circuit and the reception side circuit. A transmission / reception circuit is used, and even if an output signal is short-circuited, the transmission / reception circuit is provided with a protection circuit so as to operate reliably after the short-circuit state is released. And a detection circuit for detecting a signal transmitted by a signal line between the detection circuit and the detection circuit, and means for transmitting a signal having a predetermined content to the reception side circuit after a predetermined time by the signal. system.