Fema B RTU Series, User Manual, Page: 15 / 36

FEMA ELECTRÓNICA . SERIES B . Models Bxx-RTU
15
1.20 Registers and functions : 32 bits ‘Full Slave’
List of available registers
(see Table 21)
, available ‘coils’
(see
Table 22)
and available functions
(see Table 23)
for instru-
ments configured in ‘Full slave’ mode and 32 bits data length.
• accessing a function not listed in the table, returns error
1 ‘Illegal Function’.
• accessing a register not listed in the table, returns error
2 ‘Illegal Data Address’.
• working with 16 bit registers allows for codification of
numbers between 32767 and -32767. If higher or lower
values are codified into a register, it will force the instru -
ment to overrange or underrange the reading.
• after power loss, the instrument starts up with all regis
-
ters initialized to ‘0’
(see section 1.16).
• registers of 32 bits are written with function ‘Write Mul -
tiple Registers’. Both registers (‘high’ and ‘low’) must be
written with the same write function. If write function is
received only for one of the registers (‘high’ or ‘low’) the
instrument will discard the write function. No error code
will be generated.
• the ‘Resolution’ register contains a numerical value indi
-
cating the number of decimal places on display. Valid val -
ues from 0 to 5. Writing value 2 lights the decimal point at
position XXXX.XX. Non valid values are discarded and no
error message is generated.
• alarms can be controlled using ‘Alarm’ registers or ‘coils’.
By default, alarms are controlled by coils
(see Table 17).
To
enable the ‘Alarm’ register see section
1.21.6
. The ‘Alarm’
register is made of bits. Bit ‘0’ controls the state of Alarm 1,
bit ‘1’ control the state of Alarm 2 and bit ‘2’ controls the
state of Alarm 3
• all registers are read and write registers.
• access to reserved registers does not generate error
messages.
Register number Name
0 Display Low
1 Display High
2 Resolution Low
3 Resolution High
4 Alarms Low
5 Alarm as High
6 a 11 Reserved
Table 21 - Registers in 32 bits and ‘Full slave’ mode
‘Coil’ number Name
0 Alarm 1
1 Alarm 2
2 Alarm 3
3
4
5
6
7
Reserved
Table 22 - ‘Coils’ in 32 bits and ‘Full Slave’ mode
Function number Name
16 Write multiple registers
3 Read registers
5 Write single ‘coil’
15 Write multiple ‘coils’
1 Read ‘coils’
Table 23 - Functions in 32 bits and ‘Full Slave’ mode
Example - to update the display of the instrument to a value
of 6543.21, it is needed to work with 32 bits registers. Con -
vert the value to hex format and write to the ‘Display high’
register the first 16 bits and to the ‘Display low’ register the
last 16 bits.
654321 decimal translated to hexadecimal is 0x0009FBF1
register ‘display high’ = 0x0009 = ‘9’
register ‘display low’ = 0xFBF1 = ‘64497’
When programming, this is directly achieved with functions
DIV (integer division) and MOD (rest of integer division).
register ‘display high’ = 654321 DIV 65536 = 9
register ‘display low’ = 654321 MOD 65536 = 64497
register ‘resolution high’ = 0
register ‘resolution low’ = 2