Schneider Electric manual S7-300/400 Series

SIMATIC S7 Ethernet

*6 Data blocks are created by the user. Available addresses depend on what the user has created.

*7 PLC word addresses defined for integer, float, and string variables must be even-numbered. i.e., IW5 is not a valid device address for an integer variable. Must be either IW4 or IW6.

*8 16-bit and 32-bit data, High and Low, refer to data as defined in the following examples.

S7-300/400 Series

Device	Bit Address*1	Word Address		bit	bit
	I00000.0-I00127.7	IW00000-IW00126*7
	or	or
Input	E00000.0-E00127.7*2	EW00000-EW00126*2*7
	Q00000.0-Q00127.7	QW00000-QW00126*7
	or	or
Output	A00000.0-A00127.7*2	AW00000-AW00126*2*7		H/L*8	H/L*8
Marker	M00000.0-M00255.7	MW00000-MW00254	*7
Data Block*6	DB00001.DBX00000.0 -	DB00001.DBW00000 -
	DB00255.DBX65535.7	DB00255.DBW65534*7
Timer*3*4*5	—	T00000-T00255
		C00000-C00255
		or
Counter*3*4*5	—	Z00000-Z00255* 2

*1 Read-modify-write. When you write to one of these bit addresses, the target machine reads the entire word address, sets the defined bit, then returns the new value to the PLC. If the ladder program writes data to this word address during the bit read/write process, the resulting data may be incorrect.

*2 German variable name.

*3 Timers and Counters (T&C Devices) store special information in the top 4 bits (time base, counter up/down status etc...). The actual timer current value is stored in the lower 12 bits. Depending on which “Connection Type” is used the data returned by the PLC is in a different format. For “FETCH/WRITE” mode, the current timer/counter value is returned as Binary encoded data, but for “OP Communication” the current timer/counter value is returned as BCD encoded data.

*4 Valid range in BCD is 0000 to 0999.

*5 Read-only.

*6 Data blocks are created by the user. Available addresses depend on what the user has created.

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