105BCommunication processor
12.4 Universal serial interface (USS) communication
S7-1200 Programmable controller
574
System Manual, 11/2011, A5E02486680-05
12.4.4
USS_RPM instruction
Table 12- 40 USS_RPM instruction
LAD / FBD
SCL
Description
USS_RPM(REQ:=_bool_in_,
DRIVE:=_usint_in_,
PARAM:=_uint_in_,
INDEX:=_uint_in_,
DONE=>_bool_out_,
ERROR=>_bool_out_,
STATUS=>_word_out_,
VALUE=>_variant_out_,
USS_DB:=_fbtref_inout_);
The USS_RPM instruction reads a parameter from
a drive. All USS functions associated with one USS
network and PtP communication port must use the
same data block. USS_RPM must be called from a
main program cycle OB.
Table 12- 41 Data types for the parameters
Parameter type
Data type
Description
REQ
IN
Bool
Send request: When true, REQ indicates that a new read request is
desired. This is ignored if the request for this parameter is already
pending.
DRIVE
IN
USInt
Drive address: DRIVE is the address of the USS drive. The valid range is
drive 1 to drive 16.
PARAM
IN
UInt
Parameter number: PARAM designates which drive parameter is written.
The range of this parameter is 0 to 2047. On some drives, the most
significant byte can access PARAM values greater than 2047. See your
drive manual for details on how to access an extended range.
INDEX
IN
UInt
Parameter index: INDEX designates which Drive Parameter index is to be
written. A 16-bit value where the Least Significant Byte is the actual index
value with a range of (0 to 255). The Most Significant Byte may also be
used by the drive and is drive-specific. See your drive manual for details.
USS_DB
INOUT
USS_BASE
Then name of the instance DB that is created and initialized when a
USS_DRV instruction is placed in your program.
VALUE
IN
Word, Int, UInt,
DWord, DInt,
UDInt, Real
This is the value of the parameter that was read and is valid only when
the DONE bit is true.
DONE
1
OUT
Bool
When true, indicates that the VALUE output holds the previously
requested read parameter value. This bit is set when USS_DRV sees the
read response data from the drive. This bit is reset when either: you
request the response data via another USS_RPM poll, or on the second
of the next two calls to USS_DRV
