Chapter 8. Communication Functions
8-85
8.4.3 Function block
1) No protocol receiving function block (DRCV)
Function block Description
Input
REQ: Execute function block at the rising edge
CH: Set communication channel (0 ~ 1)
RCV_FORM: Set receiving method
- When the high byte is H00: receive the frame that the size is
designated in the low byte
- When the high byte is H01: receive the same data that is designated in
the low byte.
Output
RCV_DATA : A variable name saving the data receive
(the no. of array should be equal or more than the data size)
NDR: When it ends without error, this is set to 1 and remains 1 until the next
request for function block.
ERR: When an error occurs, this is set to 1 and remains 1 until the next request
for the function block.
STATUS : When an error occurs, this displays an error code
RCV_BYTE: The number of the received byte
(1) Function
• For No Protocol Communication, the received data is saved in RCV_DATA array under the condition that they are received
following the RCV_FORM. The length of the received data is saved in RCV_BYTE, and it is only executed when the input
condition is On.
• NDR is On when the low byte is receiving the same length of frame as it is specified, when the high byte of RCV_FORM is h00.
That is, if h000A is designated, NDR is On when 10 bytes of frame is received.
NDR is On when the low byte is receiving the same length of frame as it is specified, when the high byte of RCV_FORM is h01.
That is, if h0104 is designated, it searches H04 in the received frame and receives the data from the start point to H04, and then
NDR is On.
• The communication status is saved in ‘SS’ .
(2) Program example
• When the execution condition %MX0 is on, when the
format of RCV_FORM frame (ETX(h03) is received,
they are saved in _RCV_DA following the received
order.
• When NDR is on, the total bytes of the received
frames are saved in RCV_BYTE.
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