Data representation of the Modbus protocol
Digital
All digital data is coded by a single bit:
"0" for OFF
"1" for ON.
All digital variables are assigned to bits of consecutive registers,
each one having:
the lower-address variable assigned to the less significant bit
the higher-address variable assigned to the most significant
bit.
Analogue and integer data
An analogue and integer value is represented by a 16-bit WORD
register in binary notation. For each register, the first byte
contains the high order bits and the second byte contains the
low order bits.
The analogue variables are represented in tenths:
for example, the value 10.0 is transmitted as 0064h=100d
for example, the value –10.0 is transmitted as FF9Ch=–100d
The integer variables are transferred using the effective
value:
for example, the value 100 is transmitted as 0064h=100d
The address card operates on registers where one register must
be considered at 16-bit.
In case the BMS or supervisory system tries to write a value of a
parameter that is out of range, the writing will be ignored.
Implemented error code
Code
Modbus interpretation
1
Illegal function
Defining the BMS setting
Activating the Modbus protocol
The Modbus protocol is activated by setting the h23 parameter to 1.
This is a user parameter, refer to "How to consult and modify the user
parameters" on page 11.
Defining the unit's serial address
To
define
each
unit's
unique
communication with the supervisionary system, set parameter h10.
This is a user parameter, refer to "How to consult and modify the user
parameters" on page 11.
EWLQ014~064KBW1N
Condenserless water-cooled water chillers
DEPMHP0110817EU
Condition
Message is not supported or the
number of variables required is greater
than the allowed limit (length ≤20)
serial
address
required
Variables database
The BMS or supervisory system and the chiller unit communicate
through a fixed set of variables, also called address numbers.
Hereafter, you will find the information you need about the digital,
integer and analogue variables that the BMS or supervisory system
can read from or write to the address card of the chiller.
For addresses of all the direct and user parameters refer to
"Overview of the direct and user parameters" on page 10.
Overview of all variables which are not direct or user
parameters
Description
1=A1, HP1, or LP1
Circuit alarm
alarm codes active
0=no alarm code active
1=FL alarm code
General alarm
0=no alarm code active
1=E1, E2, or E3 alarm
NTC Probe alarm
0=no alarm code active
Input of flowswitch
alarm
Input of
changeable digital
S7S input
Input of high
pressure or
discharge protector
or overcurrent
alarm
Input of low
pressure switch
alarm
Input of
changeable digital
S9S input
Output of
compressor 1
Output of
compressor 2
Output of pump
Output of reversing
valve
Output of alarm
On or off
for
Cooling or heating
(*) D=digital.
Modbus
address
Read
41
only
Read
45
only
Read
codes
46
only
1=closed
Read
53
0=open
only
1=closed
Read
54
0=open
only
1=closed
Read
55
0=open
only
1=closed
Read
56
0=open
only
1=closed
Read
57
0=open
only
1=on
Read
59
0=off
only
1=on
Read
60
0=off
only
1=on
Read
61
0=off
only
1=on
Read
62
0=off
only
1=on
Read
63
0=off
only
1=on
Read/
64
0=off
write
1=cooling
Read/
65
0=heating
write
Operation manual
Parameter
(*)
type
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
14