West Control Solutions Pro-EC44 - Manual (Page 120)

Pro-EC44 2-Loop Graphical Profile Controller & Recorder
Pro-EC44 Product Manual - 59540-1 October 2013 Page 113
Function Code Exception
Code Modbus
Meaning Description
The original
function code with
its most significant
bit (MSB) set. This
offsets it by 0x80,
so for example
0x06 becomes
0x86. 00 Unused None.
01 Illegal function Function number is out of range.
02 Illegal Data
Address Write functions: Parameter number is out of range or
not supported. (for write functions only).
Read Functions: Start parameter does not exist or
the end parameter greater than 65536.
03 Illegal Data
Value Attempt to write invalid data / required action not
executed.
Note: In the case of multiple exception codes for a single query, the Exception
code returned is the one corresponding to the first parameter in error.
Modbus Parameters
The register addresses for the Modbus parameters are detailed in the tables below.
The Access column indicates if a parameter is read only (RO) or if it can also be written to
(R/W). Communications writes will not be implemented if the Writing Via Serial Comms
parameter in the Communications Configuration sub-menu is set to Disabled.
Data Formats
Data can be accessed in three formats: Integer Only (decimal places are not included),
Integer with 1 Decimal Place (only the first decimal place value is included) or an IEEE /
Motorola (big endian) Floating Point Number. Where possible use floating point numbers
especially if the values have more than one decimal place.
Parameter Register Address Listings
Calculating Parameter Register Addresses
Integer Only Integer+1 Floating Point
Register Address Calculation
(hex) Address Address + 0x4000 Address x 2 + 0x8000
(dec) Address Address + 16384 Address x 2 + 32768
Address Example:
(For Loop 1 Process Variable) (hex) 0x0407 0x4407 0x880E
(dec) 1031 17415 34830
Data Value Returned:
If actual Value = 23.9 decimal (hex) 0x00, 0x17 0x00, 0xEF
0x41, 0xBF, 0x33, 0x33
(dec) 23 239
23.9 as floating decimal
The register address offset calculations are shown above.
For your convenience, the parameter
tables on the following pages show each parameter’s
Modbus register address as a decimal and hexadecimal number for all three formats.
The tables also show if the parameter has read-only (RO) or read-write (RW) access.
Analogue parameter values and their limits are expressed as decimals.
Bit parameters list the bit positions and their meaning (bit 0 = LSB). Only bits that have a
function are listed, unused bits are omitted.
Note: Read only parameters will return an exception if an attempt is made to
write values to them.
Some parameters that do not apply for a particular configuration will still accept
read / writes (e.g. attempting to scale a linear output which has not been fitted).