Change the input conditions to a latched relay.
However if you turn OFF and ON the power during execution of the instruction while the input condition is set to a latched relay, the JW-20CM will come to the following state.
F-204/205 instruction processing which is being executed is deleted, and rising edge of input signal can not be detected for the input condition is kept ON so that this instruction can not be executed.
All flags (07354 to 07357) are turned to OFF. Detect them with the timer, and operate the next instruction after resetting the input conditions.
(1)Instruction system

The PC's application instruction F-202/203 (open channel), F-204 (sending instruction), and F-204 (receive instruction) to send and receive data between modules in a network, and from a module in a network to an upper stream computer is used.

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.

· SEND/RECEIVE functions of instruction system cannot be communicated two hierarchical layer.

Communication contents

Instruction to be used

(see page)


Specify communication target station in octal notation. (for ZW/JW-20CM)

F-202 (13-26)



Write data in the specified station (SEND instruction)

F-204 (13-27)



Read data out of the specified station (RECEIVE instruction)

F-205 (13-28)



Master station

Slave station

Slave station

Slave station



















































Writing and reading data


Input conditions of F-202/204/205 instructions should keep being ON until finishing execution of the instruction (when error flag or carry flag turns to ON.)

• If the input condition is turned OFF during execution of the instruction, the instruction ends in an 9 incomplete condition. Under this condition, next, when this instruction is given, it will come to a “communication jam,” and the instruction will not be executed. Turn the power OFF and then ON

again for recovery.

Take any measure for the cases below:

In case that on instantaneous power failure of min. 10ms occurs and the input conditions turn to OFF.



Note: The SEND/RECEIVE instruction is not allowed to use 10 to 2C(H) as the file numbers for the communication target station. The data memory start system can use these numbers.