JPS6138896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a loop transmission system in which a plurality of data signal processing devices mutually transfer signals using a ring-shaped unidirectional transmission path, in which a frame, which is a unit of information transfer, is transmitted over the transmission path. The present invention relates to a loop transmission system capable of detecting the number of frames when a plurality of frames exist.

Conventionally, this type of loop transmission system has been designed so that only one frame carrying data circulates. However, as the scale of the transmission system increases, the number of transmission devices increases and the total length of the transmission path increases, resulting in a plurality of frames circulating. When a plurality of frames exist in this way, the delay time until a response signal to a sent signal is received from the partner data signal processing device becomes longer than when a single frame exists.

The number of frames that exist simultaneously on the transmission path is
This is a factor indicating the amount of transmission delay, and in order for the data signal processing device to operate efficiently, it is preferable for each data processing device to recognize the number of frames that exist simultaneously.

The number of frames that can exist simultaneously is closely related to the cable used in the transmission path, and can be estimated from the length of the cable, but this requires tedious work such as measuring the length of the cable with a tape measure.

The present invention provides a means for determining the number of frames existing in a loop transmission system without measuring the length of a cable used in a transmission path.

FIG. 1 is a diagram showing an example of a loop transmission system according to the present invention. In the figure, 1 is a circular unidirectional transmission path, 2 is a transmission device that monitors the transmission path, shapes signals, etc., and 3a and 3b are The data signal processing device 4 is a frame signal carried by the transmission line 1. For example, this frame signal is given transmission data by the data signal processing device 3a and is transmitted to the other party's data signal processing device 3b.

In the Lube transmission system, on the one-way transmission path,
There may be one or more frames.

In the example shown in FIG. 1, there are three frames 4, and each frame 4 includes a synchronization word SYN indicating the beginning of the frame, and an area used to determine the number of frames on the transmission path 1. fnx(x=1,
2…………) is included.

FIG. 2 is a detailed diagram of the transmission device 2 of FIG. 1. Regarding the transmission device 2 in the figure, only the parts related to the present invention are shown. In the figure, CT1 is an n-ary counter that counts with modulus n, TIM is an operation timing generation circuit of transmission device 1, ZD is a zero detection circuit that determines whether the fnx area in a frame is zero, and RG holds the number of frames. CT2 is a counter for adding a number to the frame to distinguish between multiple frames existing on the transmission path; CP is a comparator for controlling the counting length of counter CT2; 101 to 107 are This is a signal line that interconnects these and the transmission line 1.

The timing generating circuit TIM generates pulses at the same period as the length of the frame.

N-ary counter CT1 is a timing generation circuit
Count the pulse signals of the TIM output 101 and send them to the signal line 102 with 0, 1, 2, ......, (n-1),
Outputs a cyclic number of 0, 1, ...... The above numerical value is the value of the frame 4 passing through the transmission device 2.
They are sequentially written into the fnx area and sent to transmission line 1. Frame 4 circulates through transmission path 1 and returns to transmission device 2 again, and fnx in frame 4 enters zero detection circuit ZD via signal line 103. When the zero detection circuit ZD determines that the value of fnx is zero,
The output of the counter CT1 is transferred to the frame number holding register RG via the signal line 102. The value of the contents of this frame number holding register RG is 1.
The value obtained by adding up is the number of frames existing on transmission path 1.

On the other hand, data signal processing devices 3a and 3b connected to transmission line 1 control data transfer by knowing the frame sequence number with the modulus of the number of frames 4 when a plurality of frames exist on transmission line 1. becomes easier.

This sequence number is created as follows. The n-ary counter CT2 counts the output pulses 101 of the timing generation circuit TIM. Output 10 of counter CT2
4 and the output 10 of the frame number holding register RG
5 are compared by the comparator CP, and when the two match, the signal line 106 becomes significant, and the counter CT2
When the next pulse 101 is applied to
2 is reset to zero.

In this way, the value of the frame number holding register RG (temporarily assumed to be a) is set as the maximum value, and the counter CT2
repeats counting in cycles of 0, 1, 2, ..., a, 0, 1 .... The output of the counter CT2 is written to the frame 4 via the signal line 104 and sent to the transmission line 1. At the same time, the value of the frame number holding register RG may also be written to frame 4 and sent.

As described above, the number of frames that exist simultaneously on transmission path 1 and the frame order number are set to frame 4.
The data signal processing device 3 connected to the transmission line 1 can easily know the number of frames and the frame sequence number.

As described above, according to the transmission device according to the present invention, an n-ary counter is used to send an n-ary number into a frame, and the output value area of the n-ary counter becomes zero in the frame that is returned after one cycle. By simply obtaining the value obtained by adding 1 to the output value of the n-ary counter when an object is detected, the number of frames on the transmission path of the loop transmission system can be easily determined without knowing the transmission path length. In addition, the data signal processing device connected to the transmission path can be notified of the number of frames and the sequence number of the frames, so the data signal processing device can reliably insert data into the relevant frame on the transmission path. Furthermore, the data signal processing device can perform efficient communication control by knowing the amount of propagation delay of the signal on the transmission path.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the loop transmission system of the present invention, and FIG. 2 is a diagram showing details of the loop transmission system of FIG. 1. In the figure, 1 is a transmission path, 2 is a transmission device, 3 is a data signal processing device, 4 is a frame which is the basic unit of information transmitted on a transmission path, TIM is a timing generation circuit, and CT
1, CT2 is a counter, ZD is a zero detection circuit, RG is a frame number holding register, and CP is a comparator.

Claims (1)

[Claims] 1. A transmission device, a plurality of data signal processing devices, and a transmission line are connected in a series ring, and a data signal is transmitted in one direction of the transmission path using a frame as a unit of information transfer, and the data signal is In a loop transmission system for transmitting data between processing devices, the transmission device includes a timing generation circuit, an n-ary counter, and a zero detection circuit, and the timing generation circuit is configured to transmit data when the frame passes through the transmission device. The n-ary counter counts the pulses and transfers the output to the output value area of the n-ary counter in the frame. A zero in the n-ary counter output value area is detected, and a number obtained by adding 1 to the output value of the n-ary counter at the time of the zero detection is detected as the number of frames existing simultaneously on the transmission path. Loop transmission system. 2. The loop transmission system according to claim 1, wherein the number of frames existing simultaneously on the transmission path and a sequence number whose modulus is the number of frames are sent to an area within the frame.