Sharp JW-20CM - Manual (Page 104)

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[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]
[An example of the RECEIVE function]
• 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
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]
· 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.
1 JW20/20H cannot be used as relay stations.
2 ZW-98CM/ZW-20AX cannot be used as communication target stations.
3 The maximum amount of data is 256 bytes.
Master
station 00
(8)
Slave
station 01
(8)
Slave
station 02
(8)
Slave
station 03
(8)
Request to write in
Response
Master
station 00
(8)
Slave
station 01
(8)
Slave
station 02
(8)
Slave
station 03
(8)
Request to read out
Response
Control module
JW-20CM
(Slave station 02
(8)
)
CH0
CH1
CH2
CH3
Slave
station
03
(8)
Slave
station
04
(8)
Slave
station
05
(8)
Slave
station
06
(8)