Siemens Server - Manual (Page 7)

Overview of ChemWeb Server
1
The ChemWeb Server is used for central recording, monitoring and logging of the process data in
potable and swimming pool water treatment plants. It is especially suitable for smaller installations
without process display but which are to be installed with a data recording system with simple
display. Another application example would be in unmanned plants such as potable water stations, in
which recording of the measured data is to be accomplished by remote access.
The data exchange with the MG/L 5 and metering technology is accomplished via a serial digital
interface. Data of process devices without serial digital interface can be recorded by the ChemWeb
Server by means of the process data interface (PDI). By using an RS485 bus system, a variety of
process parameters from the individual devices can be recorded, with little wiring. It is also possible
to change certain process parameters with the digital communication. Parameters such as set point
values, alarm contacts, etc. can be modified centrally via the ChemWeb Server. The RS485 bus
system can be used for distances of up to 4,000 ft (1200 m).
To fetch the measured data from the connected devices, an HTTP server is integrated in the
ChemWeb Server, the page frames of which can be called up via different interfaces depending on the
version:
- local network (Intranet)
- analog, ISDN modem
- data exchange via CompactFlash card
- serial interface RS232
The ChemWeb Server behaves as a master at the RS485 bus and therefore cannot be used in
connection with other data recording systems such as e.g. control stations, CMS, OPC servers, SECO
S7, MF485 printer logging, or Profibus DP converters.