Uss_Wpm (Change Parameters In The Drive) Instruction - Siemens S7-1200 System Manual

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Communication processor and Modbus TCP

12.4 Universal serial interface (USS) communication

Parameter type

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.

USS_WPM (Change parameters in the drive) instruction

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

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 indicates the result of the read request. Additional information is

available in the "USS_Extended_Error" variable for some status codes.

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

System Manual, 03/2014, A5E02486680-AG

S7-1200 Programmable controller