Siemens Simatic S7 Series System Manual

Libraries
9.2 USS library instructions
S7-200 SMART
420 System Manual, 09/2015, A5E03822230-AC
RUN parameter
RUN (RUN/STOP) indicates whether the drive is on (1) or off (0). When the "RUN" bit is on,
the 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 drive to ramp the speed down until the motor
comes to a stop:
● The "OFF2" bit is used to allow the drive to coast to a stop.
● The "OFF3" bit is used to command the drive to stop quickly.
Resp_R parameter
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 CPU receives a
response from the drive, the "Resp_R" bit is turned on for one scan and all the following
values are updated:
Parameter
Description
F_ACK
(fault
acknowledge)
Bit that acknowledges a fault in the drive. The drive clears the fault ("Fault" bit)
when "F_ACK" goes from 0 to 1.
DIR
(direction)
Bit that indicates in which direction the drive should move.
Drive
(drive address)
Input for the address of the drive to which the USS_CTRL command is to be sent.
Valid addresses: 0 to 31
Type
(drive type)
Input that selects the type of drive
Speed_SP
(speed setpoint)
Drive speed as a percentage of full speed:
• Negative values of "Speed_SP" cause the drive to reverse its direction of rota-
tion.
• Range: -200.0% to 200.0%
Error Byte that contains the result of the latest communications request to the drive. The
USS protocol execution error codes (Page 428) define the error conditions that
could result from executing the instruction.
Status Raw value of the status word returned by the drive. The figures below show the
status bits for standard status word and main feedback.
Speed
Drive speed as a percentage of full speed. Range: -200.0% to 200.0%
Run_EN
(RUN enable)
Indicates the drive condition:
• Running (1)
• Stopped (0)
D_Dir
Indicates the drive's direction of rotation

Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.