105BCommunication processor
12.4 Universal serial interface (USS) communication
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
575
Parameter type
Data type
Description
ERROR
OUT
Bool
Error occurred: When true, ERROR indicates that an error has occurred
and the STATUS output is valid. All other outputs are set to zero on an
error. Communication errors are only reported on the USS_PORT
instruction ERROR and STATUS outputs.
STATUS
OUT
Word
STATUS indicates the result of the read request. Additional information is
available in the "USS_Extended_Error" variable for some status codes.
1
The DONE bit indicates that valid data has been read from the referenced motor drive and delivered to the CPU. It does
not indicate that the USS library is capable of immediately reading another parameter. A blank PKW request must be
sent to the motor drive and must also be acknowledged by the instruction before the parameter channel for the specific
drive becomes available for use. Immediately calling a USS_RPM or USS_WPM FC for the specified motor drive will
result in a 0x818A error.
12.4.5
USS_WPM instruction
Note
EEPROM write operations (for the EEPROM inside a USS drive)
Do not overuse the EEPROM permanent write operation. Minimize the number of EEPROM
write operations to extend the EEPROM life.
Table 12- 42 USS_WPM instruction
LAD / FBD
SCL
Description
USS_WPM(REQ:=_bool_in_,
DRIVE:=_usint_in_,
PARAM:=_uint_in_,
INDEX:=_uint_in_,
EEPROM:=_bool_in_,
VALUE:=_variant_in_,
DONE=>_bool_out_,
ERROR=>_bool_out_,
STATUS=>_word_out_,
USS_DB:=_fbtref_inout_);
The USS_WPM instruction modifies a parameter in the
drive. All USS functions associated with one USS
network and PtP communication port must use the
same data block.
USS_WPM must be called from a main program cycle
OB.
Table 12- 43 Data types for the parameters
Parameter and type
Data type
Description
REQ
IN
Bool
Send request: When true, REQ indicates that a new write 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.