Fema B RTU Series, User Manual, Page: 4 / 36

FEMA ELECTRÓNICA . SERIES B . Models Bxx-RTU
4
1. Identify the instrument format
(see section 1.7)
2. Power and signal connections
- open the instrument
(see section 1.8)
- connect the power
(see section 1.10)
- connect the signal
(see section 1.11)
- close the instrument
(see section 1.8)
3. Configure the instrument (see section 1.21)
- select the working mode, and the bus configuration
(see
section 1.21.2)
- configure the protocol
(see section 1.21.7)
4. Advanced configuration (optional)
- configure the instrument alarms (see section 1.21.8)
- configure the fast access
(see section 1.21.11)
- configure other functions: ‘on power up’
(1.21.13)
, key
‘LE’
(1.21.20)
and password
(1.21.21)
5. If the instrument includes analog output (AO) or serial
communications (RTU, S4, S2)
- to include an option to an instrument see section
1.9
- to configure an installed option, access the option con -
figuration menu
(see section 1.21.25)
- see section 2 for information regarding the output and
control options available
6. Install the instrument
- mount on panel, wall or hanging
(see section 1.23)
- adjust the brightness level according to your environmen -
tal needs
(see section 1.21.24)
1.3 How to use this manual
If this is the first time you are configuring a Series B large
format meter, below are the steps to follow to install and
configure the instrument. Read all the manual sections in
order to have a full and clear view of the characteristics of
the instrument. Do not forget to read the installation precau -
tions at section
1.24
.
The Modbus RTU protocol is a serial communications proto -
col, based on RS-485 bus, with ‘master’ / ‘slave’ architecture.
Modbus RTU elements needed to understand this manual
are described below:
• ‘registers’: are memory sections inside the ‘slave’ in -
strument, where the ‘master’ reads or writes data. Reg -
isters store numerical data. Modbus works with registers
of 16 bits, which allows for numerical values from 32767
to -32767. For displays with 6 digits (display values from
999999 to -199999) registers of 32 bits are needed
(see
section 1.21.5)
.
• ‘coils’: are memory sections inside the ‘slave’ instrument,
where the ‘master’ reads or writes data. Coils store binary
data (‘1’ or ‘0’). Coils are typically used for alarm control
and other elements with 2 states : ‘on’ and ‘off’.
• ‘functions’: are actions that indicate to write or read val
-
ues into ‘registers’ or ‘coils’
(see Table 1)
.
• ‘errors’ : Modbus is a protocol with a ‘master’ / ‘slave’ ar -
chitecture and the ‘master’ will always expect a reply from
the ‘slave’. If a requested ‘function’, ‘register’ or ‘coil’ is not
available, the ‘slave’ will answer with an error. See section
1.15
for a list of errors available.
1.4 Modbus RTU definitions
Function Name Description
6 Write single register writes on a single register
16 Write multiple regis -
ters
writes on multiple registers
3 Read registers reads on multiple registers
5 Write single coil writes on a single coil
15 Write multiple coils writes on multiple coils
1 Read coils reads on multiple coils
Table 1 - Modbus RTU supported functions