Siemens SIMATIC S7-300 Series User Manual

Cycle and Reaction times
3-9
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
Bus Runtimes in the PROFIBUS Subnet
If you have used STEP 7 to configure your PROFIBUS subnet, STEP 7 calculates
the expected normal bus cycle time. On the PG you can then view the bus cycle
time of your configuration (refer to the STEP 7 User Manual).
An overview of the bus runtime is provided in Figure 3-4. In this example, we
assume that each DP slave has an average of 4 bytes of data.
Bus runtime
Number of DP slaves
6 ms
4 ms
2 ms
124816 32
Baud rate: 12
Mbit/s
Baud rate: 1.5 Mbit/s
1 ms
3 ms
5 ms
7 ms
Min. slave
interval
64
Figure 3-4 Overview of the Bus Runtime on PROFIBUS-DP at 1.5 Mbps and 12Mbps
Take the bus cycle time into consideration for every master when operating a
PROFIBUS subnet with more than one master. That is, bus cycle time total = bus
cycle time  number of masters.

Siemens SIMATIC S7-300 Series Specifications

General

Programming Languages	LAD, FBD, STL, SCL, GRAPH
Operating Temperature	0°C to 60°C
Storage Temperature	-40°C to 70°C
Protection Class	IP20
Processor	Depends on CPU model (e.g., CPU 315-2 DP has 16-bit processor)
Memory	Depends on CPU model (e.g., CPU 315-2 DP has 256 KB work memory)
Communication Interfaces	MPI, PROFIBUS DP, Ethernet (depending on model)
Power Supply	24 V DC or 120/230 V AC (depends on power supply module)
Digital Inputs	Depends on module (e.g., 8, 16, 32 channels)
Digital Outputs	Depends on module (e.g., 8, 16, 32 channels)
Analog Inputs	Depends on module (e.g., 8, 16 channels)
Analog Outputs	Depends on module (e.g., 2, 4)
Relative Humidity	5% to 95% non-condensing
Mounting	DIN rail