waveform Records

Normal Operation

With waveform records, the format converter is applied to each array element. Between the elements, a separator is printed or expected as specified by the Separator variable in the protocol. When parsing input, a space as the first character of the Separator matches any number of any whitespace characters.

During input, a maximum of NELM elements is read and NORD is updated accordingly. Parsing of elements stops when the separator does not match, conversion fails, or the end of the input is reached. A minimum of one element must be available.

During output, the first NORD elements are written.

The format data type must be convertible to or from the type specified in the FTVL field. The types "INT64" and "UINT64" are only available in EPICS base version 3.16 or higher.

The variable x[i] stands for one element of the written or read value.

DOUBLE format (e.g. %f):
Output: x[i]=double(VAL[i])
FTVL can be "DOUBLE", "FLOAT", "INT64", "UINT64", "LONG", "ULONG", "SHORT", "USHORT", "CHAR", "UCHAR", or "ENUM" (which is treated as "USHORT").
Input: VAL[i]=FTVL(x[i])
FTVL must be "FLOAT" or "DOUBLE"
LONG or ENUM format (e.g. %i or %{):
Output: x[i]=long(VAL[i])
FTVL can be "INT64", "UINT64", "LONG", "ULONG", "SHORT", "USHORT", "CHAR", "UCHAR", or "ENUM" (which is treated as "USHORT").
Signed values are sign-extended to long, unsigned values are zero-extended to long before converting them.
Input: VAL[i]=FTVL(x[i])
FTVL can be "DOUBLE", "FLOAT", "INT64", "UINT64", "LONG", "ULONG", "SHORT", "USHORT", "CHAR", "UCHAR", or "ENUM" (which is treated as "USHORT").
The value is truncated to the least significant bytes if FTVL has a smaller data size than long.
STRING format (e.g. %s):
Output: x[i]=VAL[i]
Input: VAL[i]=x[i]
Note that this is an array of strings, not an array of characters.
In this case, the complete waveform is treated as a large single string of size NORD. No separators are printed or expected.
Output: x=range(VAL,0,NORD)
The first NORD characters are printed, which might be less than NELM.
Input: VAL=x, NORD=length(x)
A maximum of NELM-1 characters can be read. NORD is updated to the index of the first of the trailing zeros. Usually, this is the same as the string length.
Other values of FTVL are not allowed for this format.


During initialization, the @init handler is executed, if present. All format converters work like in normal operation.