Section 8.  Operation 
 
 
 
 
8.10.3.2.2  CRBasic Instructions (Modbus) 
Complete descriptions and options of commands are available in CRBasic Editor 
Help. 
ModbusMaster() 
Sets up a CR800 as a Modbus master to send or retrieve data from a Modbus 
slave. 
Syntax 
ModbusMaster(ResultCode, ComPort, BaudRate, ModbusAddr, 
Function, Variable, Start, Length, Tries, TimeOut) 
ModbusSlave() 
Sets up a CR800 as a Modbus slave device. 
Syntax 
ModbusSlave(ComPort, BaudRate, ModbusAddr, DataVariable, 
BooleanVariable) 
MoveBytes() 
Moves binary bytes of data into a different memory location when translating big-
endian to little-endian data.    See the appendix Endianness
 (p. 559). 
Syntax 
MoveBytes(Dest, DestOffset, Source, SourceOffset, NumBytes) 
ReadOnly() 
Set a variable to read only. 
Syntax 
ReadOnly() 
 
8.10.3.2.3  Addressing (ModbusAddr) 
Modbus devices have a unique address in each network.    Addresses range from 1 
to 247.  Address 0 is reserved for universal broadcasts.    When using a network 
of dataloggers in a Modbus over Pakbus configuration, use the same number for 
both the  Modbus address and the PakBus address. 
If a slave is to echo back requests to the master, enter the address of the slave as a 
negative number in ModbusMaster().