Siemens Simatic M7-400 Reference Manual page 625

System function block
A system function block (SFB) is a ³ function block integrated in the operating
system of the CPU that can be called in the STEP 7 user program like a function
block (FB), as required. The associated instance data block is in working
memory.
Temperature coefficient
Parameter in STEP 7 for analog input modules when measuring temperatures
with a resistance thermometer (RTD). The temperature coefficient you select de-
pends on the resistance thermometer being used (to DIN standard).
Transmission rate
Rate of data transmission (bit/s)
Two-conductor/three-conductor/four-conductor connection
Method of connection to the module – for example, of resistance
thermometers/resistors to the front connector of the analog input module or of
loads at the voltage output of an analog output module.
Two-wire transmitter/four-wire transmitter
Kind of transmitter (two-wire transmitter: supply (via terminals of the analog input
module; four-wire transmitter: supply via separate terminals of the transmitter)
Ungrounded
Without galvanic connection to ground
User program
The user program contains all the statements, ³ declarations and data for signal
processing required to control a system or process. It is assigned to a
programmable module (CPU, FM, for example) and can be structured in smaller
units (blocks).
Varistor
Voltage-dependent resistor
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Glossary
Glossary-19