JP4019987B2 - Data frame configuration method for serial communication - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a serial communication function for transmitting and receiving cyclic data used in the field of industrial machines such as machine tools and semiconductor manufacturing apparatuses.
[0002]
[Prior art]
In recent years, in the machine tool and semiconductor manufacturing equipment industries, etc., it has become a trend to construct a network system that connects serial communication between a command device and a plurality of motor drive devices and various sensors for the purpose of remote operation and wiring saving. ing.
[0003]
For example, in FIG. 5, 51 is a command device as a master, 52 is a motor drive device as a slave, and these communication lines are daisy chain connected to transfer data cyclically by serial communication.
[0004]
Examples of data that must be updated cyclically and must be updated early include command data such as position command, speed command, and torque command, and response data includes current position, current speed, and torque (current value). There is. In addition, parameters that can be updated late or that do not require cyclic data transfer processing itself include parameter setting and reading of software version information.
[0005]
For data that needs to be transferred cyclically, it is possible to perform advanced control such as cooperative control by ensuring the simultaneity of data update between servo drives. Further, the control performance and monitoring performance of the entire system can be improved by increasing the update rate of these data, that is, shortening the communication cycle.
[0006]
When adding data that may be slow to update, or cyclically transferring data that does not require cyclic transfer processing itself, it is natural to compare it with transferring only data that needs to be updated quickly. In particular, it is necessary to take measures such as increasing the data size per cycle and extending the cycle. As a result, the control performance and monitoring performance of the entire system are degraded. In order to suppress this degradation in performance, the conventional technology divides the data that may be late to update or data that does not require cyclic update processing itself into a plurality of cycles instead of transferring all the data in one cycle. (For example, refer to Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-244218
[Problems to be solved by the invention]
However, in the above conventional technique, as a breakdown of data used in one slave, data that needs to be updated earlier and data that does not require cyclic transfer processing itself may be mixed. If there are slaves with different required update rates, it is necessary to match the communication cycle with the slave A group that must have a fast update rate. A good slave B group was over-specification, and as a result, there was a problem of reducing transmission efficiency.
[0009]
Conversely, when the communication cycle is adjusted to the slave B group, there is a problem of reducing the control performance.
[0010]
Therefore, as shown in FIG. 6, when the slave A group and the slave B group are daisy chain connected to separate loops, the master side must have a plurality of communication loops, which raises costs and complicates the system. It was.
[0011]
The present invention solves the above-described conventional problems, and improves the transmission efficiency when slaves with different data update rates required are connected together on the same serial communication loop, thereby achieving optimum data transfer. An object is to provide a serial communication function that can be performed.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a data update of a slave A group in which slaves having different required data update rates are mixed and connected on the same loop , and the data update rate must be fast. In the data frame configuration of the network system in which the data update rate is set to an integral multiple of the set communication cycle for the slave B group that may set a communication update rate according to the rate and the data update rate may be slow, And a single data field that combines command data transmitted from the master to a part of the slave A group and the slave B group, and a single data field that combines response data returned to the master, At the beginning of the data field, the address of the corresponding slave is a bit unit. The header field shown in Fig. 5 is added, and the slave data shown in this address area is combined in a predetermined order, and the slave data contained in the data field is extracted with the configuration of only the header field bit length address area. Enable.
[0013]
As a result, it is possible to increase the transmission efficiency when slaves with different data update rates are connected together on the same serial communication loop, and to enable optimum data transfer.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above-mentioned problem, a data frame configuration method of serial communication according to claim 1 includes a command device as a master, a motor drive device (hereinafter referred to as group A) as a plurality of slaves, an overtravel limit A communication loop in which sensors and temperature sensors (hereinafter referred to as Group B) are daisy chained to form a communication loop, cyclically transferring data, and updating data with multiple slave A groups that need to update data quickly. A plurality of slave B groups may be connected on the same loop, and a communication cycle is set to the required data update rate of the slave A group, and the data update of the slave B group is performed at an integral multiple of the communication cycle. I do.
[0015]
This data frame configuration method forms one data field that combines command data transferred from a master to a plurality of slaves within one cycle, and similarly, response data returned from a plurality of slaves to a master. Are combined, and an address field indicating the addresses of a plurality of slaves in bit units is added to the head of each data field, and the slave data indicated in the address area is determined in advance. The slave data contained in the data field can be extracted by combining them in order and only having a bit length address area of the header field. By checking the address field in the header of the data to determine whether there is data corresponding to each slave's own address in the data transferred every cycle, a plurality of slave data is included in the data within one cycle. Even if they are mixed, the corresponding data can be accurately captured by the slave. In addition, the data size is reduced and the transmission efficiency is improved by the configuration in which this address is indicated in bit units.
[0016]
In addition, if serial communication is performed using the data frame configuration of the present invention with a plurality of motor drive devices that need to update data quickly, optimal motor drive can be realized while increasing the transmission efficiency of complicated commands. it can.
[0017]
【Example】
Hereinafter, a command device and a motor drive device having a serial communication function will be described with reference to the drawings as an embodiment of the present invention.
[0018]
In FIG. 1, the direction of the arrow indicates the flow of communication data. A master 11 (for example, a command device), one slave A group 12 and two slave B groups 13 are daisy chained in one loop. Connected.
[0019]
Here, the slave A group 12 (for example, a motor drive device) that has a short cycle and needs to perform data transfer quickly has a data update rate of 500 μsec, and the slave B group 13 (overtravel that may have a slow data transfer). The data update rate required for the limit sensor, temperature sensor, etc.) is set to 2 msec, which is four times (integer multiple) of the slave A group.
[0020]
An example of data update at this time is shown in FIG. 2, and data is transmitted to the slaves of addresses of all slave A groups 12 (2 units) and slave B group 13 (8 units) from “cycle 1” to “cycle 4”. This indicates that the transmission is completed and the first “cycle 1” is returned in “cycle 5”.
[0021]
At the beginning of each period, data (data 21 and data 22) of two addresses (No. 0 and No. 1) corresponding to the slave A group 12 are provided and transmitted, and two addresses of the slave A group 12 are transmitted every period. Update the data.
[0022]
Further, in “cycle 1”, two addresses (No. 2) from the slave B group 13 following the data (data 21 and data 22) of the addresses (No. 0 and No. 1) of the slave A group 12 are displayed. And No. 3) data (data 23 and data 24) are transmitted, and the data is updated. In the next “cycle 2”, the slave A group 12 address (No. 0 and No. 1) data (data 21 and data 22) are followed by another two addresses (No. .4 and No. 5) data (data 25 and data 26) are transmitted, and the data is updated.
[0023]
The subsequent cycles are the same, and after the address data of the slave A group 12, two data (data 27 and data 28) or (data 29 and data 2A) of the slave B group 13 are transmitted to update the data. To do.
[0024]
As a result, during the period from “cycle 1” to “cycle 4”, the master 11 has completed transmission of data to all of the ten slaves (slave A group and slave B group).
[0025]
During this time, the data update of the slave A group 12 is four times and the data update of the slave B group 13 is one time. Therefore, if one cycle length is set to 500 μsec, the data update rate of the slave A group 12 is also 500 μsec, and the data update rate of the slave B group 13 is four times (4 cycles), 2 msec.
[0026]
As a result, it is not necessary to update the data in the slave B group 13 at an unnecessarily fast cycle, and the length of the data field within one cycle is constant, so that the transmission efficiency can be increased.
[0027]
FIG. 3 shows an example of the configuration of a data frame of one cycle. A header field 31 is provided at the head of the data frame, and the header field 31 includes an address area. Subsequently, the data field 32 and the footer field 33 are divided.
[0028]
As shown in the address part (in the case of 16 bits) in FIG. 3, the address field included in the header field 31 has the least significant bit as “address No. 0” and the most significant bit as “address No. 15”. If a certain bit in this address area is 1, it indicates that slave data having the corresponding address exists in the data field transferred in this cycle (in FIG. Address No. 0, No. 3, No. 6, and No. 9).
[0029]
The data field 32 has a configuration in which, for example, the data size for each slave is set to 2 bytes in advance, and each 2-byte data continues from the top of the field in ascending order of the address number. In this way, each slave can accurately read data corresponding to its own address.
[0030]
FIG. 4 is obtained by adding the header field address part (in the case of 16 bits) to the data field in FIG. 0, No. 1, no. 2, No. A bit of 3 indicates 1, which means that the data of the slave having the corresponding address exists in the data field transferred in this cycle.
[0031]
That is, instead of adding a corresponding address to each data for each slave, it is possible to extract data included in the data field 32 with only a bit length address area of the header field 31. The data frame length of the cycle can be shortened, and the transmission efficiency can be increased.
[0032]
In the present embodiment, the motor driving device is used as the slave A group. However, the present invention is not limited to this, and any control target that needs to update data quickly may be used.
[0033]
【The invention's effect】
As is apparent from the above embodiment, according to the invention described in claim 1, even when slaves having different data update rates are connected together on the same loop, transmission is possible. Efficiency can be increased and optimal data transfer can be achieved.
[0034]
According to the second aspect of the invention, by applying to the motor drive device, it is possible to realize the optimum motor drive while increasing the transmission efficiency of the complicated command.
[Brief description of the drawings]
FIG. 1 is a daisy chain connection diagram of serial communication in one embodiment of the present invention. FIG. 2 is a configuration diagram of data transmitted from a master to a slave in one embodiment of the present invention. FIG. 4 is a data configuration diagram of a data frame in one embodiment of the present invention (addition of an address area).
Fig. 5 Daisy chain connection diagram in conventional serial communication Fig. 6 Other daisy chain connection diagram in conventional serial communication
11 Master 12 Slave A group 13 Slave B group 21, 22 Slave A group address 23-29, 2A Slave B group address 31 Header field 32 Data field 33 Footer field

Claims (2)

A single master and a plurality of slave A groups that need to update data early and a plurality of slave B groups that may update data are connected on the same communication loop, and cyclically transfer data In the data frame configuration of the network system in which the serial communication cycle is set to the required data update rate of the slave A group and the data of the slave B group is updated at an integral multiple of the cycle, within one cycle And a single data field that combines command data transmitted from the master to a part of the slave A group and the slave B group, and a single data field that combines response data returned to the master, Header indicating the address of the corresponding slave in bit units at the beginning of the data field By adding a field and combining the slave data shown in this address area in the predetermined order, it is possible to extract the slave data contained in the data field with only the address area of the bit length of the header field A data frame composition method of serial communication characterized by the above. The serial communication data frame construction method according to claim 1, wherein the slave A group is a motor drive device.

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