Sharp JW-21MN manual Description for Data Link Operation, Communication method, Relay link

Chapter 9: Description for Data Link Operation

The data link function is used to send and receive ON/OFF signals (relay link) and data (register link) between modules by assigning one module from PCs or FA devices as the master station and other units as slave stations in the satellite net system. Up to 64 sets of PCs and FA devices can be connected in the satellite net.

Each station sends data in its sending area cyclically and stores data received from other stations in its receiving area. For the JW-21MN to execute automatically these sending and receiving procedures, a special program for communications is required.

When the JW-21MN is assigned as a slave station, it has the standard function and save memory function for data link, but the data contents for receiving from other stations is different between these two functions. (When the JW-21MN is used as a master station, only the standard function is available.) [When all of a master station and slave stations are JW-21MN]

- Master station	Data link (Standard function) Receiving data of all of the relay link area and
	all of the register link area of all the stations.
- Slave station	Data link (Standard function) ｝
	Data link (Save memory function)	In order to effectively use the
		memory, unify a partial data area or
		sending/receiving address (program)
		of slave stations.

For the standard function and the save memory function of the JW-21MN, see page 15-2.

9-1 Communication method

[1] Data link (Standard function)

Each station cyclically sends and receives ON/OFF signals and data of the relay link area and register link area set to a master station parameter.

(1)Relay link

Mainly used for sending and receiving ON/OFF information

[Example] In the case of sending 1-byte data from a master station and slave stations 01 and 02.

9

Master station (PC00) Slave station (PC01) Slave station (PC02)

コ０２００ コ０２０１ コ０２０２

PC00 Program	PC01 Program	PC02 Program
	02000	02000
	02000
02010		02010
		02010
02020	02020

02020

：Send ：Receive

- The link relay of the receiving station must be programmed as input signal by the PC program- ming. Also, it may be used as source (S) side of application instruction.

- The sending and receiving data correspond in bits of one point unit.

(Master station)

(Slave station)

７

６

５

４

３

２

１

０

７

６

５

４

３

２

１

０

コ０２００

コ０２００

Is the same value as ｺ0200 of the master station.

７

６

５

４

３

２

１

０

７

６

５

４

３

２

１

０

コ０２０１

コ０２０１

Is the same value as ｺ0201 of the slave station.

9-1