IDEC microsmart pentra, Programming Manual

Page: 315 / 344

FT1A S
MART
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XIS
U
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S
M
ANUAL
FT9Y-B1382 25-19
25: U
SER
C
OMMUNICATION
I
NSTRUCTIONS
Example 2: BCC is calculated for the first byte through the sixth byte using the ADD format, converted in binary to ASCII, and
compared with the BCC code appended to the seventh and eighth bytes of the incoming data.
Receive Completion Output
Designate an output, Q0 through Q21, or internal relay, M0 through M1277, as a device for the receive completion output.
When the start input for a RXD instruction is turned on, preparation for receiving data is initiated, followed by data conversion and
storage. When a sequence of all data receive operation is complete, the designated output or internal relay is turned on.
Conditions for Completion of Receiving Data
After starting to receive data, the RXD instruction can be completed in three ways depending on the designation of end delimiter and delimiter in the
receive format.
Note: Whenever a receive timeout has occurred, data receiving is stopped arbitrarily.
Data receiving is completed when one of the above three conditions is met. To abort a RXD instruction, use the special internal relay for user
communication receive instruction cancel flag. See page 25-20.
Example: A RXD instruction does not have an end delimiter and has a delimiter programmed in the receive format for data
registers.
“1”
(31h)
“2”
(32h)
BCC Calculation Range
“3”
(33h)
“4”
(34h)
Incoming Data
“5”
(35h)
“6”
(36h)
“0”
(30h)
“7”
(37h)
BCC
31h + 32h + 33h + 34h + 35h + 36h = 135h
“3”
(33h)
“5”
(35h)
BCC Calculation Result
Binary to ASCII Conversion
Comparison result is false.
Error code 9 is stored in the receive status data
register.
End Delimiter Delimiter Conditions for Completion of Receiving Data
With With or Without
When a specified byte count of data (digits  repeat) has been received or when an end delimiter is
received. When a BCC exists immediately after the end delimiter, the BCC is received before ending
data receiving.
Without With
After the last constant (including delimiter) designated in the RXD instruction has been received, data
receiving is completed when the subsequent byte count of data has been received.
Without Without When a specified byte count of data (digits  repeat) has been received.
Receive Format
DR1 FFh BCC
1 byte 4 bytes max. + delimiter 1 byte 2 bytes max.
DR2
Delimiter: FFh 
Conversion: ASCII to Binary 
Digits: 4 
Repeat: 1
Delimiter: — 
Conversion: None 
Digits: 2 
Repeat: 1
After delimiter FFh has been received, data
receiving is completed when subsequent 3
bytes are received.