Siemens Simatic S7-200 System Manual page 328

S7-200 Programmable Controller System Manual
USS_CTRL Instruction
The USS_CTRL instruction is used to control an active MicroMaster
drive. The USS_CTRL instruction places the selected commands in
a communications buffer, which is then sent to the addressed drive
(Drive parameter), if that drive has been selected in the Active
parameter of the USS_INIT instruction.
Only one USS_CTRL instruction should be assigned to each drive.
Some drives report speed only as a positive value. If the speed is
negative, the drive reports the speed as positive but reverses the
D_Dir (direction) bit.
The EN bit must be on to enable the USS_CTRL instruction. This
instruction should always be enabled.
RUN (RUN/STOP) indicates whether the drive is on (1) or off (0).
When the RUN bit is on, the MicroMaster drive receives a command
to start running at the specified speed and direction. In order for the
drive to run, the following must be true:
-
Drive must be selected as Active in USS_INIT.
-
OFF2 and OFF3 must be set to 0.
-
Fault and Inhibit must be 0.
When RUN is off, a command is sent to the MicroMaster drive to
ramp the speed down until the motor comes to a stop. The OFF2 bit
is used to allow the MicroMaster drive to coast to a stop. The OFF3
bit is used to command the MicroMaster drive to stop quickly.
The Resp_R (response received) bit acknowledges a response
from the drive. All the Active drives are polled for the latest drive
status information. Each time the S7-200 receives a response from
the drive, the Resp_R bit is turned on for one scan and all the
following values are updated.
11
The F_ACK (fault acknowledge) bit is used to acknowledge a fault in the drive. The drive clears the fault
(Fault) when F_ACK goes from 0 to 1.
The DIR (direction) bit indicates in which direction the drive should move.
The Drive (drive address) input is the address of the MicroMaster drive to which the USS_CTRL command
is to be sent. Valid addresses: 0 to 31
The Type (drive type) input selects the type of drive. For a MicroMaster 3 (or earlier) drive, set Type to 0.
For a MicroMaster 4 drive, set Type to 1.
Table 11-3
Inputs/Outputs
RUN, OFF 2, OFF 3, F_ACK, DIR
Resp_R, Run_EN, D_Dir, Inhibit,
Fault
Drive, Type
Error
Status
Speed_SP
Speed
316
Parameters of the USS_CTRL Instruction
Data Types
BOOL
BOOL
BYTE
BYTE
WORD
REAL
REAL
Operands
I, Q, M, S, SM, T, C, V, L, Power Flow
I, Q, M, S, SM, T, C, V, L
VB, IB, QB, MB, SB, SMB, LB, AC, *VD, *AC, *LD, Constant
VB, IB, QB, MB, SB, SMB, LB, AC, *VD, *AC, *LD
VW, T, C, IW, QW, SW, MW, SMW, LW, AC, AQW, *VD, *AC, *LD
VD, ID, QD, MD, SD, SMD, LD, AC, *VD, *AC, *LD, Constant
VD, ID, QD, MD, SD, SMD, LD, AC, *VD, *AC, *LD