7-18
Section
Data Control Instructions
425
Description
SCL3(––) is used to linearly convert a 4-digit 4-digit BCD value to 4-digit signed
hexadecimal. SCL3(––) converts the BCD value according to a specified linear
relationship. The conversion line is defined by the y-intercept and the slope of
the line specified in the parameter words P1 to P1+2.
When the execution condition is OFF, SCL3(––) is not executed. When the
execution condition is ON, SCL3(––) converts the 4-digit BCD value in S to the
4-digit signed hexadecimal value on the line defined by the y-intercept (0, P1)
and the slope (P1+2
÷
P1+1) and places the result in R. The result is rounded off
to the nearest integer.
The content of S can be 0000 to 9999, but S will be treated as a negative value if
CY=1, so the effective range of S is actually –9999 to 9999. Be sure to set the
desired sign in CY using STC(40) or CLC(41).
Parameter words P1+3 and P1+4 define upper and lower limits for the result. If
the result is greater than the upper limit in P1+3, then the upper limit is written to
R. If the result is less than the lower limit in P1+4, then the lower limit is written to
R.
Note
The upper and lower limits for a 12-bit Analog Input Unit would be 07FF and
F800.
The following table shows the functions and ranges of the parameter words:
Parameter
Function
Range
P1
x-intercept (signed hex.)
8000 to 7FFF (–32,768 to 32,767)
P1+1
∆
X (BCD)
0001 to 9999
P1+2
∆
Y (signed hex.)
8000 to 7FFF (–32,768 to 32,767)
P1+3
Upper limit (signed hex.)
8000 to 7FFF (–32,768 to 32,767)
P1+4
Lower limit (signed hex.)
8000 to 7FFF (–32,768 to 32,767)
The following diagram shows the source word, S, converted to R according to
the line defined by the point (0, P1) and slope
∆
Y/
∆
X.
S
Value after conversion
(Signed hexadecimal)
R
Value before conversion
(BCD)
Y-intercept
∆
X
∆
Y
Lower limit
Upper limit
The result can be calculated by first converting all BCD values to signed binary
and then using the following formula.
R
+
ǒ
D
Y
D
X
S
Ǔ
)
P1
Flags
ER:
Indirectly addressed DM word is non-existent. (Content of *DM word is
not BCD, or the DM area boundary has been exceeded.)
The content of S is not BCD.
CY:
CY is not changed by SCL3(––). (CY shows the sign of S before execu-
tion.)
EQ:
ON when the result, R, is 0000.
