Siemens Simatic S7 Series System Manual

Special memory (SM) and system symbol names
D.4 SMB2: Freeport receive character
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
669
D.4
SMB2: Freeport receive character
Special memory byte 2 is the Freeport receive character buffer. Each character that is
received while in Freeport mode is placed in this location for easy access by your program.
Table D- 3 SMB2 Freeport received character
S7-200 SMART
symbol name
SM address
Description
Receive_Char SMB2 This byte contains each character received from Port 0 or Port 1 during Freeport com-
munication.
Note
SMB2 and SMB3 are shared between port 0 and port 1
When the reception of a character on port 0 results in the execution of the interrupt routine
attached to that event (interrupt event 8), SMB2 contains the character received on
port 0,
and SMB3 contains the parity status of that character.
When the reception of a character on port 1 results in the execution of the interrupt routine
attached to that event (interrupt event 25), SMB2 contains the character received on port 1,
and SM
B3 contains the error status of that character.
D.5
SMB3: Freeport character error
SMB3 is used for Freeport mode and contains an error bit that is set when a parity, framing,
break, or overrun error is detected on a received character. SM3.0 is set ON when a parity,
framing, break, or overrun error is detected. Use this bit to discard the message.
Table D- 4 SMB3 Freeport character error
S7-200 SMART
symbol name
SM address
Description
Parity_Err SM3.0 This bit indicates a parity, framing, break, or overrun error received from Port 0 or
Port 1. (0=no error; 1=error)

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.