ParmToBuff

(Engine-Level Function)

Description:	Returns a buffer of formatted numeric parameter values.
Returns:	Buffer
Usage:	Script Only.
Function Groups:	Advanced Module,  String and Buffer
Related to:	ArrayToBuff | BuffToArray | BuffToParm
Format:	ParmToBuff(Object, Index, N, Option, Size, Skip [, BadData])
Parameters:

Object

Required. Any object (the object value of any running module instance).

Index

Required. Any numeric expression giving the first parameter to format, starting from 1.

N

Required. Any numeric expression giving the number of parameters to format. If there are fewer actual parameters than N + Index, this statement stops at the last parameter.

Option

Required. Any numeric expression which specifies the format of the buffer read. Option Format 0 Unsigned binary (low byte first) 1 Signed binary (low byte first) 2 BCD (binary coded decimal) (low byte first) 3 ASCII octal (high byte first) 4 ASCII decimal (high byte first) 5 ASCII hex (high byte first) 6 ASCII floating point (high byte first) 7 IEEE float/double (low byte first) 8 <obsolete> 9 Allen-Bradley® PLC/3 floating point 10 VAX single precision floating point

Size

Required. Any numeric expression giving the number of digits in each datum. It has a different meaning for each option as indicated: Option Size Meaning Size Range Binary types  Number of bits  1 - 32 bits BCD  Number of 4-bit digits  1 - 8 digits ASCII types  Number of bytes  1 - 32 bytes Float types  Precision  1 for single precision,  2 for double precision For Options 7 and 9 the data is written as appropriate binary format.

Skip

Required. Any numeric expression giving the number of buffer bits/digits/bytes to skip after writing each non-floating point element. For floating point types, this parameter must be set to 0.

BadData

An optional parameter that designates how invalid data is to be handled, according to the following table:   Defaults to 0 if missing or invalid. BadData Handled 0 Output to buffer as invalid values 1 Causes buffer to be invalid 2 Output to buffer as valid 0s

Comments:

This function may only be used with parameters containing numeric data. It is useful for encoding serial port data when writing I/O drivers.

Example:

If a module call looks like:

Write(1, 2, 3, x, y, z);

And there is a statement in module Write that looks like:

If ! Valid(writePacket);
[
  writePacket = ParmToBuff(Self(){ Current module },
                           4 { Skip first 3 parameters },
                           NParm(Self()) - 3
                           { Use rest of parameters },
                           0 { Unsigned binary format },
                           16 { Bits },
                           0 { No skip });
]

Because this statement encodes x, y, and z as 16 bit unsigned integers, the returned buffer will be 16 bytes long, byte-ordered as follows:

Byte	Description
0	Low byte of x
1	High byte of x
2	Low byte of y
3	High byte of y
4	Low byte of z
5	High byte of z