Sharp JW-20CM, JW-20RS [4]SEND/RECEIVE function

[4]SEND/RECEIVE function

Different from the data link, the SEND/RECEIVE functions are functions which exchange the data of the required station of the required time between a PC and a personal computer or between PCs. The SEND function is the function which writes in the data after assigning the station to send data to, and the RECEIVE function is the function which reads out the data.

[An example of the SEND function]

Master	Slave	Slave	Slave
station 00(8)	station 01(8)	station 02(8)	station 03(8)

			Request to write in
				Response
[An example of the RECEIVE function]
	Master	Slave			Slave	Slave
	station 00(8)	station 01(8)			station 02(8)	station 03(8)

Request to read out

Response

•In this instruction, the function is completed after the target station replies. A special program is not needed in the connected PC station. If the target station is an upper computer, a program is required for response after decoding the SEND/RECEIVE instructions.

But if the upper computer cannot decode the SEND/RECEIVE instructions, these instructions

9 can not be used.

•The data route for the SEND/RECEIVE functions between the control module and this module is called a “channel.” Each module has four channels, CH0 to CH3, and is able to transfer a maximum of 256 bytes of data. Therefore, four operations of SEND/RECEIVE functions can be executed simultaneously on a ladder program.

[Example]

JW-20CM

Control module (Slave station 02(8))

CH0

CH1

CH2

CH3

Slave	Slave	Slave	Slave
station	station	station	station
03(8)	04(8)	05(8)	06(8)

·There are the “instruction system” and the “data memory starting system” as the starting system in SEND/RECEIVE functions.

You can select the starting system in each channel using a parameter.

·With the "Data memory start system," the JW-20CM can communicate across different hierarchies of the satellite net. However, this type of communication has the following limitations.

1JW20/20H cannot be used as relay stations.

2ZW-98CM/ZW-20AX cannot be used as communication target stations.

3The maximum amount of data is 256 bytes.

9·6