FW-E112-P-MAN-EN_v0101_08
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APPENDIX C: COMMUNICATION VARIABLES
GENERAL
The tables below show the various variables that can be used for communication.
The E112-P is fitted with the Modbus communication protocol and can be equipped with various physical
interfaces like RS485 and RS232 (please see device datasheet for available options).
Currently, the functions supported are function 3
Read Holding Registers
(4X references) and function 16
Preset Multiple Registers (4X references). The shown communication variables, indicated by the column
VAR, show protocol addressed in decimal representation, followed by its hexadecimal representation
(0x0000). When the PLC address range is required (4X references typically used by PLCs), please add a
value of 40001 to the protocol address. E.g. reading the serial number with PLC-based addressing means
reading 165 + 40001 = register 40166.
Variables spanning multiple registers use ‘little-endian’ data representation. This means that the lowest
register holds the least significant word of the variable. Although most Modbus masters will support
variables that span 2 registers, variables spanning more registers sometimes require you to manually
calculate the resulting value.
Following example shows how data is represented and how this calculation can be accomplished:
For a total-value of 158928, the following register data has been received by the Modbus master:
register 566 = 0x6CD0 = 27856
register 567 = 0x0002 = 2
register 568 = 0x0000 = 0
If we interpret this as a long integer value, it's value would be: 0x0000.0002.6CD0 = 158928.
If this value needs to be calculated: 0*65536*65536 + 2*65536 + 27856 = 158928.
For additional information regarding using your Fluidwell Modbus device, please read the ‘Fluidwell
General Modbus Communication Protocol’ and ‘Modbus troubleshooting guide’ that are available through
our website or your distributor.
RUNTIME VARIABLES OF THE E112-P
VAR
RUN-TIME VALUES REGs R/W TYPE
VALUE / REMARKS
572
0x23C
flow rate
2
r
uint32 0…9999999
Representation: unit, time, decimals
depending on variables 48, 49, 50
566
0x236
total 3
r
uint48 0…9999999999
Representation: unit, decimals
depending on variables 32, 33
560
0x230
accumulated total
3
r
uint48 0…99999999999999
Representation: unit, decimals
depending on variables 32, 33
37
0x025
error status
1
r
uint16 Bitfield:
0x0001=Display error
0x0002=EEPROM error
0x0004=EEPROM initialization error
0x0010= IO configuration error
0x0020= IO configuration error
0x0040=Linearization error (calculated M-
factor out of range)
Reading flowrate, total or accumulated total: The returned values are given including the decimals and
represent the actual value. The given value may differ from the value that is displayed on the display – this
is due to the fact that the display is limited in the number of digits and may have a slower update rate set.
For example when two decimals are selected for total and total has a value of 123456,78 the display will
show 23456,78 while communication will read a “total” of 12345678 and a “total decimals” of 2.
Clearing total: It is possible to clear the total counter by means of writing a value of 0 to all the 3 registers of
total in a single write action. Writing any other value will result in the reply of an error message.
