Siemens SIMATIC S7-1200

Communication processor and Modbus TCP
13.7 Legacy USS communication (CM/CB 1241 only)
S7-1200 Programmable controller
1244 System Manual, V4.2, 09/2016, A5E02486680-AK
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 instruc-
tion 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 re-
sult in a 0x818A error.
13.7.3.4
USS_WPM (Change parameters in the drive) 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 13- 126 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 net-
work and PtP communication port must use the same
data block.
USS_WPM must be called from a main program cycle
OB.