17: U
SER
C
OMMUNICATION
I
NSTRUCTIONS
17-18
O
PEN
N
ET
C
ONTROLLER
U
SER
’
S
M
ANUAL
Skip
When “skip” is designated in the receive format, a specified quantity of digits in the incoming data are skipped and not
stored to data registers. A maximum of 99 digits (bytes) of characters can be skipped continuously.
Example: When a RXD instruction with skip for 2 digits starting at the third byte is executed
BCC (Block Check Character)
The
OpenNet Controller
has an automatic BCC calculation function to detect a communication error in incoming data. If a
BCC code is designated in the receive format of a RXD instruction, the
OpenNet Controller
calculates a BCC value for a
specified starting position through the position immediately preceding the BCC and compares the calculation result with
the BCC code in the received incoming data. The start position for the BCC calculation can be specified from the first byte
through the 15th byte. The BCC, calculated in either XOR or ADD, can be 1 or 2 digits.
When an end delimiter is not used in the RXD instruction, the BCC code must be positioned at the end of the receive for-
mat designated in Source 1 operand. When an end delimiter is used, the BCC code must be immediately before or after the
end delimiter. The
OpenNet Controller
reads a specified number of BCC digits in the incoming data according to the
receive format to calculate and compare the received BCC code with the BCC calculation results.
BCC Calculation Start Position
The start position for the BCC calculation can be specified from the first byte through the 15th byte. The BCC is calculated
for the range starting at the designated position up to the byte immediately before the BCC of the receive data.
Example: Received data consists of 17 bytes plus 2 BCC digits.
(1) Calculation start position = 1
(2) Calculation start position = 2
0035h
D102
“1”
(31h)
“2”
(32h)
Skipped
“3”
(33h)
“4”
(34h)
Incoming Data
0038h
D105
0036h
D103
“5”
(35h)
“6”
(36h)
“7”
(37h)
“8”
(38h)
0031h
D100
0032h
D101
0037h
D104
When D100 is designated
as the first data register
STX
BCC calculation range
1st
“A”
2nd
“B”
3rd
“C”
4th
“D”
5th
“E”
6th
“0”
15th
CR
16th
LF
17th
BCC
18th
BCC
19th
BCC
(2 digits)
STX
BCC calculation range
1st
“A”
2nd
“B”
3rd
“C”
4th
“D”
5th
“E”
6th
“0”
15th
CR
16th
LF
17th
BCC
18th
BCC
19th
BCC
(2 digits)
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
