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Glossary

S7-400 Automation System Module Data

464 Reference Manual, Edition 09/2009, A5E00850736-06

PROFIBUS DP

Digital, analog and intelligent modules, along with a wide range of field devices complying

with IEC 61784-1:2002 Ed1 CP 3/1, such as drives or valve clusters are moved away from

the automation system to the local process over distances of up to 23 km.

The modules and field devices are interconnected with the automation system over the

PROFIBUS DP Fieldbus and are addressed in the same way as centralized I/O.

Programming device

A programming device (PG) is a personal computer with a special compact design, suitable

for industrial conditions. A programming device is completely equipped for programming the

SIMATIC automation systems.

RC element

Connection of ohmic resistor and capacitor in series. When a consumer is turned off, an

overvoltage occurs in circuits with an inductive load that can cause an electric arc and can

reduce the life of the contacts. To extinguish this electric arc, the contact can be bridged by

an RC element.

Reaction time

The reaction time is the time from detecting an input signal to changing the output signal

associated with it.

The actual reaction time is between a longest and a shortest reaction time. When configuring

a plant, the longest reaction time must always be assumed.

Reference channel error

Parameter in STEP 7 for analog input modules. This parameter enables the error group

message of the reference junction when using thermoelements. A reference channel error

occurs when using thermoelements:

● When a fault occurs (for example broken wire) in a reference channel to which a

thermoresistor (RTD) is connected (channel 0) to compensate temperature drift.

● When the → reference temperature is outside the permitted range of values.

Each input channel to which the reference junction "RTD on channel 0" is assigned has the

reference channel error in the situation described above - the measured temperature is no

longer compensated.

Reference junction

Parameter in STEP 7 for analog input modules. This parameter specifies the reference point

(point with known temperature) when using the thermoelements. Reference points can be:

Thermoresistor on channel 0 of the module; → compensating box, → reference temperature.

Reference potential

Potential on the basis of which the voltages of the circuits involved are measured.

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Siemens S7-400PLC Especificaciones Pagina 464