Siemens S7-300 (Ethernet:ISO over TCP/IP) Addressing

 

 

Memory Type		Range	Description	Read/Write	Data Type
I	I	0.00 - 65535.7	Input Memory	R/W	Bit
	IB	0 - 65536			Byte
	IW	0 - 65535			Word
	ID	0 - 65535			Double Word
Q	Q	0.00 - 65535.7	Output Memory	R/W	Bit
	QB	0 - 65536			Byte
	QW	0 - 65535			Word
	QD	0 - 65535			Double Word
M	M	0.00 - 65535.7	Internal Memory	R/W	Bit
	MB	0 - 65536			Byte
	MW	0 - 65535			Word
	MD	0 - 65535			Double Word
DB	DBX	1.0 - 65535.65535	Data Block Memory	R/W	Bit
	DBB				Byte
	DBW				Word
	DBD				Double Word
* T		0 - 255	Timer Acc.	R/W	Word
* C		0 - 255	Counter Acc.		Word

* Timers and Counters only accept values up to 999 in BCD.  If you attempt to write a value greater than 999, it will only accept the lower 12 bits (least significant 3 digits).  The upper 4 bits are used for the Time Base.  Refer to Siemens documentation for a more specific breakdown of the Timer Bit pattern.

Siemens Elementary Types	C-more Tag Data Type	Siemens Memory Types
BOOL	Discrete	I/Q/M/DBX
BYTE	Signed Int 16	IB/QB/MB/DBB
WORD		IW/QW/MW/DBW
INT
DWORD	Signed Int 32	ID/QD/MD/DBD
DINT
REAL	Floating PT 32	ID/QD/MD/DBD
CHAR	Ascii String	DBB String/DBB Char
View the PLC Variables Status	To view the Status of the Variables in the PLC, once you are Online with the PLC, from the Main Menu of the SIMATIC Manager Software, click on the PLC (1) selection and select Monitor/Modify Variables (2) from the drop-down menu as shown below. The Variables Monitoring window shown below will open.  From this window, you can enter the Variables and Monitor their states.
Data Block Addressing	Data Block Addressing syntax differs some between what is seen in the SIMATIC Software and in C-more.  To view the Data Block, double click on the specific Data Block you wish to view in the main SIMATIC Manager window.  When a specific Data Block is selected, a window like the one shown below will open.
	From the figure shown above: The image above shows DB1. Inside DB1, there are Four Variables: MOTOR_RPM is addressed at byte0 and is a 16 bit Integer. SETPOINT_RPM is addressed at byte2 and is also a 16bit Integer. START is addressed at byte 4, bit 0 and is a Boolean. STOP is addressed at byte 4, bit 1 and is a BOOLEAN. These Four Variables would be Addressed as follows in C-more: MOTOR_RPM = Memory Type:  DB.DBW  Address:  1.0 SETPOINT_RPM = Memory Type:  DB.DBW  Address: 1.2 START = Memory Type:  DB.DBX  Address:  1.4   Bit:  0 STOP = Memory Type:  DB.DBX  Address:  1.4  Bit:  1

SIMATIC Variables Addressing Siemens Vs. C-more
SIMATIC Variable	Siemens Addressing	C-more Addressing
		Memory Type	Address	Bit
MOTOR_RPM	DB1.DBW 0	DB.DBW	1.0
SETPOINT_RPM	DB1.DBW 2	DB.DBW	1.2
START	DB1.DBX 4.0	DB.DBX	1.4	0
STOP	DB1.DBX 4.1	DB.DBX	1.4	1
	Note: Please note that there is a space (shown in red on the Address sample) on all the Siemens Addressing (DB1.DBW 0). Note: The information provided above for C-more Addressing is used for the C-more PLC Address fields shown below.

 

Using the Variable #3 as a sample, the Tag Name window from C-more would look as follows: If you view these Variables in the Variable Table of the SIMATIC Manager, they look more like the C-more syntax.  To view, from the Main Menu of the SIMATIC Manager Software, click on the PLC (a) selection and select Monitor/Modify Variables (b) from the drop-down menu as shown below. The Variable Monitor Table window shown below will open.  From this window you can Monitor the Variables shown.