KROHNE Summit 8800 Vol 3 - Manual (Page 148)

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SUMMIT 8800 COMMUNICATION 08
The standard settings need to match the meter settings:
Stream Select the stream where the encoder is connected to
Baud rate The speed of transmission in bits per second between 300 and 38400.
Parity A check on correct transmission: none, odd, even, space or mark.
Stop bits Gap between two transmitted words, 1 or 2 stop bits
Mode RS232 or RS 485
Word size Size of 1 word: 7 or 8 bits
Timeout The maximum time to be waiting for a response, after which an alarm is given
8 .8 Encoder protocol
Normally meters have an index with totals, but send flow rates to flow computers in the form of
pulses. From these pulses, the flow computer calculates then calculates its own totals.
Clearly the problem is that the meter totals are normally different from the totals in the flow
computer. Differences occur because the initial meter totals are not copied to the flow computer,
not even after a flow computer is stopped.
An encoder solves that problem by including electronics into the meter index which sends the
exact the meter totals to the flow computer. Often a 2 wire NAMUR Interface is used to transmit
the data via a serial protocol. Via a converter to RS232, the encoder can be connected to the flow
computer.
The Summit will use the totals from the encoder to ensure that both totals are identical. How-
ever for flow rate the Summit still need the traditional connections, typically pulses.
Figure 199 Encoder setting
The standard settings need to match the encoder settings:
Stream Select the stream where the encoder is connected to
Baud rate The speed of transmission in bits per second between 300 and 38400.
Parity A check on correct transmission: none, odd, even, space or mark.