79SCU200 INSITE ENERGY MANAGEMENT SYSTEM
• Error Codes
Modbus protocol defines a common way of error reporting. Every request (read or write) sent in unicast
mode is expected to return a value in packet of the same structure. In case of a message delivery error
(not a CRC problem but a message execution problem), the generated response contains a function code
with MSB (80h) set and a single byte representing the error code, called “exception code”.
The following default exception codes are available:
Code Name Description
01h Illegal function Function is not supported
02h Illegal data address
Register address is out of control unit’s range, or trying to
write into a read only register
03h Illegal data value Value is out of range
04h Slave device failure
Unrecoverable error occurred while the control unit was
attempting to perform the requested action, for example,
time-out
06h Slave device busy
Control unit is currently in User Interface Configuration
Mode. Unable to execute the requested action
• Data and Control Registers
A register is always a two-byte (16-bit) value, which can be interpreted as either signed or unsigned values
or which has a special format.
In case of data represented in more than one register the concatenated registers will contain information
with MSB in the lowest address and LSB in the highest address within concatenated addresses.
Do not use registers other than those specified.
Format of one-word register for current values
unsigned = 16-bit unsigned integer notation, resolution 0.01 A
signed = 6-bit signed integer notation, resolution 0.01 A
0000h…7FEFh = 0.00 … 327.51 A
8000h…FFFFh = -327.66 … -0.01 A
7.1.1.CMS current sensor readings
• Values with special meanings
Special values (hex) Special values (dec) Meaning
7FF0 32'752 Data pending, acquisition in progress
7FF1 … 7FFB 32'753 … 32'763 Reserved
7FFC 32'764
The sensor is known but not accessible at the
moment
7FFD 32'765 Data type TrueRMS / AC / DC is disabled
7FFE 32'766 Overload (beyond full range)
7FFF 32'767 Forbidden (no sensor with ID xx)
Format of double-word register for branch power and energy values
unsigned = 32-bit unsigned integer notation,
signed = 32-bit signed integer notation
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