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REFERENCE INFORMATION
SSLBP
PROCESS DATA DESCRIPTOR
Each PTOC entry points to a process data descriptor or a mode descriptor. Each
process data descriptor is a record with fields for data size, data type, data direction,
minimum and maximum values, the address of the process data and the unit name and
process data name. Each process data element has a corresponding process data
descriptor record. In addition there are mode descriptor records that indicate the current
hardware and software modes of the remote device. The process data descriptor record
structure is as follows:
FIELD NAME FIELD LENGTH DESCRIPTION
RECORD_TYPE 8 BITS RECORD TYPE = 0xA0
DATA_SIZE 8 BITS DATA SIZE IN BITS
DATA_TYPE 8 BITS DATA ELEMENT TYPE
DATA_DIRECTION 8 BITS DATA DIRECTION
PARAM_MIN 32 BITS IEEE-754 FP PARM MIN
PARAM_MAX 32 BITS IEEE-754 FP PARM MAX
PARAM_ADD 16 BITS ADDRESS OF PARM
UNIT_STRING VARIABLE NULL TERM. STRING
NAME_STRING VARIABLE NULL TERM. STRING
PROCESS DATA DESCRIPTOR FIELDS
RECORD_TYPE
The RECORD_TYPE field is a single byte at the beginning of the process data
descriptor for record typing and sanity checking. It is 0xA0 for process data records.
DATA_LENGTH
The DATA_LENGTH field is a single byte field that specifies the length of the
process data element in bits. Minimum is 1 bit, maximum is 255 bits, however current
SSLBP implementations are limited by the number of interface registers to a maximum of
96 bits.
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