
Chapter 3
MMS and Your Coprocessor
3-18
The following list contains general information on some of the data types
listed in the preceding sections.
You can access all integer locations with either 16 or 32 bit sizes in an
MMS Type Specification. The number shown in parenthesis in the table
in Appendix A indicate the default size.
You can access all integer locations as unsigned integer. To read
integer locations as unsigned, an MMS Type Specification is required.
To write integer locations as unsigned, an MMS Type Specification is
not required.
If you want to access the integer (N) or status (S) sections as binary data
(MMS boolean or MMS bitstring), a bit–position specifier (/) must be
present in the address. For example, if you want to read bit 0 of N7:0,
the ‘‘N7:0/0” must be specified as the address even if an MMS Type
Specification stating boolean or bitstring is specified. If there is no
bit–position specifier (/) in the address, then binary access is not
allowed.
The maximum integer value that you can write into a BCD location is
9,999. To read BCD as an integer, an MMS Type Specification is
required. To write BCD as an integer, an MMS Type Specification is
not required.
You must access the ASCII file as a fixed length VisibleString or
OctetString. The maximum length of the string is bounded by the
negotiated segment size and/or the size of the file.
You access the string (ST) file as a VisibleString or an OctetString. You
can use an indefinite length; the maximum is 82 bytes. To read as an
octet string, an MMS Type Specification is required. To write as an octet
string, no MMS Type Specification is required.
You can access MMS arrays of the default type by providing the
appropriate MMS Type Specification or by specifying ‘‘size”
information in the address (for example N7:0,5 for an array of 5
integers). You note this with a comma (,), followed by the size. MMS
Type Specification and the ‘‘size” information can not both be present,
or an error is returned. There are instances where MMS array access is
not allowed. They are listed below:
- arrays of bitstrings are never allowed
- array access into ASCII (‘‘A”) file is not allowed
- array access of the ‘‘DATA” member of the message structure is not
allowed.
- array access of the ‘‘ADDR” member of the PID structure is not
allowed.
- array access of the ‘‘DATA” member of the PID structure is not
allowed.
Additional Information on
Using Data Types
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