JPH05108119A - Communication processing method using serial transmission line - Google Patents

Abstract

PURPOSE:To make the high speed of transmission by transmitting all units to require the speed for each transmission cycle out of remote I/O units and transmitting the unit which may be late, for each prescribed number of units. CONSTITUTION:In a PC(programmable controller) having a remote I/O function, for example, seven pieces of remote I/O units 4-16 are connected through a serial transmission line to a PC main body 2. That is, three increasing units 4, 6 and 8 to require the speed for the input and output response time and four special units 10, 12, 14 and 16 for which the input output data quantity is comparatively large and the response time also may be late more or less are connected. Concerning the units 4, 6 and 8, the transmission is wholy performed for each transmission cycle, and concerning the units 10, 12, 14 and 16, the transmission is performed for each prescribed number of units for each transmission cycle. Thus, the transmission cycle of the unit in which the input and output response time must be fast is shortened and the input output response time is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication processing method for transmitting input / output data between a programmable controller main body and a plurality of remote I / O units connected to the main body via a serial transmission line. It is a thing.

More specifically, the present invention relates to a communication processing method in a programmable controller (hereinafter abbreviated as PC) having a remote I / O function connected by serial transmission.

[0003]

2. Description of the Related Art In a PC having a remote I / O function connected by a serial transmission line, input / output data is communicated between a plurality of remote I / O units connected to the transmission line and the PC body. Each remote I /
A communication processing method is adopted in which input / output data transmission between the O unit and the PC main body is performed one by one, and when the number of connected units is completed, one unit is sequentially performed from the first unit.

[0004]

However, according to the conventional method, when the transmission speed is relatively slow and the number of connected remote I / O units is large, or when each remote I / O unit is connected.
If the input / output data volume of the / O unit is large,
Since the transmission time from the first unit to the last unit becomes long, there is a problem that the remote I / O unit, which requires an input / output response speed, is too slow to be used practically.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional device and to provide a remote I / O device having different input / output response speeds.
An object of the present invention is to provide a communication processing method capable of increasing the transmission speed even when O units are mixed.

[0006]

According to the present invention, in order to solve the above-mentioned problems, a programmable controller main body and a plurality of remote I / O units connected to the main body via a serial transmission line are provided. When transmitting input / output data, the plurality of remote I / O units are divided into a first group unit that requires an input / output response speed and another second group unit, and the first group unit is divided into units. Is transmitted every transmission cycle,
With respect to the units of the second group, a predetermined number of units are transmitted for each transmission cycle.

[0007]

According to the present invention, the remote I / O unit connected to the transmission line is divided into a unit that requires an I / O response speed and a unit that requires a relatively long I / O response time. The transmission cycle is not too large by transmitting all the transmission cycles for the required units, and by transmitting a predetermined number (for example, one unit) in each transmission cycle for the units that may be delayed. I have to.

[0008]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 shows a PC having a remote I / O function.
2 shows a system configuration in this embodiment. In FIG. 1, seven remote I / O units are connected to the PC body 2 via a serial transmission line. That is, three expansion units 4, 6 and 8 which require a high speed input / output response time, and four special units 10 which have a relatively large input / output data amount and may have a slightly slower response time. 12, 14, 16 are connected.

FIG. 2 shows the remote I / O in this embodiment.
The communication timing is shown. In this embodiment, input / output data of all three expansion units and one special unit is transmitted in one transmission cycle, and input / output data of all special units is transmitted in four transmission cycles.

Therefore, as compared with the conventional example in which communication is performed with all seven remote I / O units in each transmission cycle, when viewed from the extension unit side, communication can be performed in a shorter transmission cycle. Become.

[0012]

As described above, according to the present invention, in the PC having the remote I / O function, the connected remote I / O unit must have a fast input / output response time, and even if it is late, Input / output data transmission for only a predetermined number of units (for example, one unit) in one transmission cycle for units that do not matter, such as units that can be operated late (for example, those that are operated by humans or see the display) Therefore, it is possible to shorten the transmission cycle of the unit, which must have a fast input / output response time, and shorten the input / output response time.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a remote I / O communication timing in this embodiment.

[Explanation of symbols] 2 PC (programmable controller) main unit 4, 6, 8 Expansion unit 10, 12, 14, 16 Special unit

Claims (1)

[Claims] 1. When transmitting input / output data between a programmable controller main body and a plurality of remote I / O units connected to the main body via a serial transmission line, a plurality of the remote I / O units are provided. Is divided into a unit of the first group for which an input / output response speed is required and a unit of the other second group, all the units of the first group are transmitted in each transmission cycle, and the units of the second group are The communication processing method is characterized in that a predetermined number of units are transmitted for each transmission cycle.