Programming
Chapter 3
322
Figure 3.17
AF1
Division Function Input and Result Display Rungs
Bit
Storage
204
200
G
203
000
G
202
400
G
201
000
G
305
000
G
306
002
G
307
080
G
310
000
G
Execute Aux
Function
Function Number:
Data Addr:
Result Addr:
04
201
305
Error Message
If you divide by zero, the error bit (bit 14) is set and the result reads zero.
AF1 Square Root Function
The AF1 square root function operates on a 3-digit BCD integer and presents
the result in a 6-digit BCD number composed of three integer digits and 3
decimal digits. The first integer digit and the last decimal digit (digit 1 and digit
6) are always zero.
(+
XXX.)
1/2
= +XXX.XXX
A decimal point is implied between digits 3 and 4. the function calculates the
square root of the absolute input value and sets the sign bit in the output to the
sign of the input. The result is accurate to +
.01.
How to Enter an AF1 Square Root Function
To program an AF1 square root function, perform the following steps:
1. Press [SHIFT] [EAF] or [SHIFT][SCT] on the keyboard of your industrial
terminal. Figure 3.1 appears on the CRT.
2. Enter 05, the function number for AF1 square root.
This entry identifies that the function entered is to perform an AF1 square root
and that the processor use the data table format shown in Figure 3.18 when
executed. The three digits of the operand (the number whose square root you
desire) are represented in BCD by the groups of bits labeled digit 1 through 3.
The six digits of the result are labeled digit 1 through 6. Digit 1 and digit 6 in
the result are always zero.
