Siemens SIMATIC S7-300 Reference Manual page 548

OB Organization block
OP Operator panel
OS Operator system
PIQ Process-image output table
PII Process-image input table
Programming Programming device
device
PS Power supply
Q Analog output current
I
Q Analog output voltage
V
RAM Random access memory
R Load impedance
L
S + Detector lead (positive)
S– Detector lead (negative)
SF "Group error" error LED
SFB System function block
SFC System function
SM Signal module
PLC Programmable logic control
SSI Synchronous serial interface
TD Text display
U+ Measuring lead for voltage input
U Common mode voltage
CM
U Potential difference between M
iso
Sign Sign
F-2
and local ground
ANA
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03