KROHNE BM 90 EN - Manual (Page 40)

40
A PPENDIX 2 Serial Communications
BM90 L ONLY
The Level-Sonic BM90E is fitted with two serial communi-
cations channels as standard. Channel 1 has been built
for RS232 and Channel 2 for RS485. The connector is
TB5 on the top
PCB.
RS232
1. RS232 : BM90E PLC
C O M P U T E R
15M
CABLE - 3 CORE SCREENED
As only one BM90 L unit can be connected to each
RS232 serial port on the computer, and the transmission
distanc is limited, this is only likely to be used for commu-
nications within a control room.
RS485
2. RS485 : BM90E 01 BM90E 31
PLC
C O M P U T E R
1000M to further unit
CABLE - SINGLE PAIR SCREENED
This option allows up to 31 Level-Sonic BM90 L units to
be daisy-chained on the same cable, connected to a
single port on the computer. Therefore where multiple
Level-Sonic BM90E units are being used this option
should be used.
Converters / Repeaters
To interface to the Level-Sonic BM90E a computer or
PLC with the required serial port will be required. Usually
the RS232 port will be fitted as standard, with the RS485
being available as an option.
If the required serial option cannot be fitted, then signal
converters and repeaters are on the market. These will
convert RS232 to RS485 and will extend greatly the
transmission distances.
DATA COMMUNICATIONS
There are at present two types of data communications
available in the Level-Sonic BM90E Unit.
1. Commissioning System
The commissioning system allows the echoes being
received and processed by Level-Sonic BM90LE to be
downloaded to an IBM or compatible computer (usually
portable), so that they can be viewed easily. This system
has made the use of an oscilloscope for on-site cimmis-
sioning unnecessary.
To use this option requires a software package and inter-
face cables. These are detailed along with its operation in
a separate bulletin.
2. Pleed Data Transfer
This option allows an external computer to obtain data
that can be used to produce any required display i.e.
tables, mimics. The data is transmitted in a format that
can be understood and processed by any programmable
device using High or Low level languages.
The data obtained depends on the application pro-
grammed.
LEVEL
a) Level
b) Displayed value - %, volume, tonnage, etc.
c) Rate of change of level
d) Temperature
e) Status of 4 relays
f ) Loss of transducer and loss of echo
DISTANCE
a) Distance
b) Displayed value - % - ullage etc.
c) Rate of change of level
d) Temperature
e) Status of 4 relays
f ) Loss of transducer and loss of echo
DIFFERENTIAL
a) Upstream level
b) Downstream level
c) Difference of levels
d) Temperature
e) Status of 4 relays
f ) Loss of transducer and loss of echo
O C M
a) Flow rate
b) Head
c) Totaliser value
d) Temperature
e) Status of 4 relays
f ) Loss of Transducer and loss of echo
To use this option will require software to be written for
the PLC or computer that requests the data. Details of the
transmission protocols and hardware connections are
given in a sepatate bulletin.
RS 232 RS 485
TB5
Rx Tx GND SCN SCN - +