FP_ASCII_TO_BCD

ASCII -> BCD conversion

This FP instruction converts the hexadecimal ASCII codes at s1_Start to BCD characters if the trigger EN is TRUE. s2_Control specifies the number of bytes to be converted and the conversion direction.

The result is stored in d.

Parameters

Input

s1_Start (WORD, INT, UINT): Starting address
s2_Control (WORD): Number of bytes and conversion direction

Output

d (WORD, DWORD): Converted bytes

Remarks

Specifying the control code s2_Control
1. (1) data size to be converted:
  16-bit: 1–2 bytes to be converted
  
  32-bit: 1–4 bytes to be converted
2. (2) always 0
3. (3) conversion direction:
  0: forward
  
  1: reverse
The two characters that make up one byte are interchanged when stored. Two bytes are converted as one segment of data.
- Forward direction:
- Reverse direction:
ASCII HEX codes to express BCD characters:

BCD character

ASCII HEX code

0123456789

16#30 16#31 16#32 16#33 16#34 16#35 16#36 16#37 16#38 16#39

BCD character	ASCII HEX code
0123456789	16#30 16#31 16#32 16#33 16#34 16#35 16#36 16#37 16#38 16#39

ExampleSigned/unsigned 16-bit data, forward direction, 4 characters

	Offset	ASCII codes	BCD equivalent			Offset	Converted BCD characters
s1_Start	0	16#3231	21	Þ	d	0	16#3412
	1	16#3433	3			1
s2_Control		16#0004

Example16-bit data, reverse direction, 4 characters

	Offset	ASCII codes	BCD equivalent			Offset	Converted BCD characters
s1_Start	0	16#3231	21	Þ	d	0	16#1234
	1	16#3433	43			1
s2_Control		16#1004

Example32-bit data, forward direction, 8 characters

	Offset	ASCII codes	BCD equivalent			Offset	Converted BCD characters
s1_Start	0	16#3231	21	Þ	d	0	16#3412
	1	16#3433	3			1	16#7856
	2	16#3635	65			2
	3	16#3837	87			3
s2_Control		16#0008

Example32-bit data, reverse direction, 8 characters

	Offset	ASCII codes	BCD equivalent			Offset	Converted BCD characters
s1_Start	0	16#3231	21	Þ	d	0	16#5678
	1	16#3433	43			1	16#1234
	2	16#3635	65			2
	3	16#3837	87			3
s2_Control		16#1008

Example32-bit data, reverse direction, 7 characters

If an odd number of characters is being converted, 0 will be entered for bit position 0–3 of the last converted byte if the conversion direction is "forward". If the conversion direction is "reverse", 0 will be entered for bit position 4–7:

	Offset	ASCII codes	BCD equivalent			Offset	Converted BCD characters
s1_Start	0	16#3231	21	Þ	d	0	16#4567
	1	16#3433	43			1	16#0123
	2	16#3635	65			2
	3	16#3837	87			3
s2_Control		16#1007

Error flags

sys_bIsOperationErrorHold (turns to TRUE and remains TRUE)

if the area specified using the index modifier exceeds the limit.
if ASCII characters other than 16#30–16#39 are specified
if the number of bytes specified by s2_Control is greater than the area specified by s1_Start
if the conversion result is greater than the data area specified by d
if s2_Control = 0
if the conversion direction is out of range
if the number of bytes specified in s2_Control is greater than 8

sys_bIsOperationErrorNonHold (turns to TRUE for one scan)

if the area specified using the index modifier exceeds the limit.
if ASCII characters other than 16#30–16#39 are specified
if the number of bytes specified by s2_Control is greater than the area specified by s1_Start
if the conversion result is greater than the data area specified by d
if s2_Control = 0
if the conversion direction is out of range
if the number of bytes specified in s2_Control is greater than 8

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		bStart: BOOL:=FALSE;
			(*activates the function*)
		wASCIIInput: WORD:=16#3031;
		wControlCode: WORD:=16#2;
			(*specifies the operation:
digit 0: the number of bytes
to convert
digit 1,2: has to be zero
digit 3: nomal or reverse direction*)
		wConversionResult: WORD:=0;
			(*result after a 0->1 leading
edge from start:
[16#2033,0]*)
	END_VAR

POU body

When the variable bStart is set to TRUE, the function is carried out. Two characters of the ASCII input value are converted in forward direction

LD body

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 6 ;
        NETWORK_BODY
B(B_CONTACT,,bStart,5,2,7,4,);
B(B_VARIN,,wASCIIInput,11,3,13,5,);
B(B_VARIN,,wControlCode,11,4,13,6,);
B(B_VAROUT,,wConversionResult,23,3,25,5,);
B(B_F,FP_ASCII_TO_BCD!,,13,1,23,6,,?DEN?Ds1_Start?Ds2_Control?AENO?Cd);
L(1,3,5,3);
L(7,3,13,3);
L(1,0,1,6);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

if bStart then
    FP_ASCII_TO_BCD(s1_Start := wASCIIInput, 
                    s2_Control := wControlCode, 
                    d => wConversionResult);
END_IF;