Rice Lake SCT-30 - Manual (Page 16)

12 SCT-30 Weight Transmitter Manual
Tot. bytes = 3+2*No. registers+2
where: No. of registers = number of Modbus registers to be read, starting
from register 1 address;
No. of bytes = number of following data bytes;
In the event of a string received correctly but not executable, the slave responds with
an EXCEPTIONAL RESPONSE. The FUNCTION field is transmitted with the msb
at 1.
The communication strings are controlled by CRC (Cyclical Redundancy Check).
In case of a communication error the slave will not respond with any string. The
master must allow for a time-out before response reception and if no response is
received, it infers that a communication error has occurred.
Registers and Values
The instrument ModBus registers may only be read.
H - L: high half and low half - respectively, making up the DOUBLE WORD value.
RESPONSE
Address Function No. bytes Register1 Register 2 2 bytes
A 0x03 0x04 0x0064 0x00C8 CRC
EXCEPTIONAL RESPONSE
Address Function Code 2 bytes
A Funct + 0 x 80 CRC
CODE DESCRIPTION
1 ILLEGAL FUNCTION (Function not valid or not supported)
2 ILLEGAL DATA ADDRESS (The specified data address is not available)
3 ILLEGAL DATA VALUE (The data received have no valid value)
REGISTER DESCRIPTION
40007 Status Register
40008 H Divisions
40009 L Divisions