JPH0216071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission system in which it is necessary to collect analog amounts at a plurality of information generation points in one place with temporal simultaneity.

A conventional device of this type is shown in FIG.

In the figure, 1 is the first remote terminal unit (hereinafter referred to as RTu), 2 is the second remote terminal unit (hereinafter referred to as RTu), and 3 is the Nth terminal unit (hereinafter referred to as RTuN). Each is a data generation point.

4 is the master terminal unit (hereinafter referred to as MTu)
5 is a sampling command generation station.
Further, 6 indicates a data transmission path, 7 indicates a sampling command transmission path, 8 indicates one frame for data transmission,
10 is a fixed time slot for RTu1, 11
is a fixed time slot for RTu, 12 is
Fixed time slot for RTuN3.

Next, the operation will be explained. In Figure 1,
RTu 1 RTu 2, RTuN 3 are remote terminal units (slave stations for data transmission and reception) located at analog quantity generation points, and data sampling commands are sent to these RTu from sampling command generation station 5 synchronously and simultaneously to each RTu. is given via the sampling command transmission line 7.

Each RTu 1, 2, and 3 samples and holds the analog amount to be transmitted at that sampling timing, performs A/D conversion, and then puts the data in the time slot 8 assigned to each RTu of the data transmission frame. Transmit up to MTu4.
In MTu, data transmission frames are sent in sequence after a certain period of time after a sampling command is issued.
Collect RTu data.

Conventional data transmission equipment of this type is configured as described above, so it requires a sampling command generation station and a transmission line for that purpose in order to synchronize each RTu. Since the data is sent to each RTu all at once, there is a drawback that the distribution of RTu is limited by the distance from the sampling command station.

This invention was made to eliminate the drawbacks of the conventional devices as described above, and provides a data transmission device that is inexpensive and has a simple configuration by eliminating the sampling command station and the sampling command transmission line. The purpose is to

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 2, 1 is RTu, 2 is RTu,
3 is RTuN, 4 is MTu, 6 is data transmission line,
15 to 17 are sampling delay time correction circuits, 8
is a data transmission line frame, 9 is a synchronization word, 1
3 is a dummy slot, 14 is a dummy slot N, 10 is a slot, 11 is a slot, 12
is slot N.

The RTu1 located at the farthest end from the MTu4 sends out a data transmission frame 8 every sampling period of the system. Each RTu1, 2, and 3 performs A/D conversion using the timing at which the synchronization word SYN9 is received as the sampling timing, loads the data into the assigned slot, and transmits it to the MTu4.
In order to use the synchronization word as the sampling timing, dummy slots 13 to 14 corresponding to the data establishment time in the RTu are provided between the slots assigned to each RTu 1, 2, and 3 and the synchronization word. Furthermore, since the synchronization word is used as the sampling timing, the timing at which each RTu actually performs sampling is different. However, since this is a fixed time determined only by the transmission speed and the number of bits of the synchronization word, as long as the output of the MTu is used as an analog value, sampling delay time correction circuits 15, 16, and 17 must be prepared after receiving it at the MTu. Therefore, correction becomes possible.

In the above embodiment, the transmission line 6 has a party line shape, but it may also have a loop shape, and in this case, the frame generation station may be an MTu.

As described above, the present invention has the advantage that the system can be configured at low cost because the device and transmission line dedicated to sampling commands can be omitted, and there is a considerable degree of freedom in the distribution of RTu because the transmission is relayed. be.

[Brief explanation of drawings]

Figures 1a and b are block configuration diagrams and signal frame configuration diagrams of a transmission device that synchronizes the sampling time of a conventional RTu, and Figures 2a and b are diagrams of a transmission device that uses the synchronization word of the present invention as a sampling command. 1 is a block configuration diagram and a signal frame configuration diagram showing one embodiment. FIG. In the figure, 1...RTu, 2...RTu,
3...RTuN, 4...MTu, 5...Sampling command generation station, 6...Data transmission line, 7...Sampling command transmission line, 8...Signal frame,
9...Synchronization word, 10...Fixed time slot for RTu, 11...Fixed time slot for RTu, 12...Fixed time slot for RTuN,
13...Dummy slot, 14...Dummy slot N, 15...Sampling delay time correction circuit for RTu, 16...Sampling delay time correction circuit for RTu, 17...Sampling delay time correction circuit for RTuN. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. Data is transmitted using the timing at which the synchronization word is received as the sampling timing of a data transmission frame in which a dummy slot corresponding to the data establishment time at the synchronization signal reception station is inserted between the synchronization word and the assigned slot of the synchronization signal reception station. a plurality of remote terminal units, a data transmission line sequentially connecting each of the remote terminal units, and a master terminal unit connected to the final stage of the plurality of terminal units;
A transmission device comprising a plurality of sampling delay time correction circuits connected to the master terminal unit.