Lenze SCF Series Drives Modbus Communications - Manual (Page 9)

5 RG-SFMOD
Data & Register Format
3 Data Representation - Internal and External
3.1 Register Format
All registers are 16 bits. The data within these registers can take on the following forms:
• Individual bit commands (16 per register).
Example: Register #1 (Modbus Register #2).
• Individual bit flags (16 per register).
Example: Register #22.
• A chain of two 8 bit unsigned integers.
• A 16 bit unsigned integer.
This unsigned integer could in turn represent many different types of data with various scaling
rules and units, which are defined by the DATA TYPE of the register.
3.2 Data Types
Data passed in registers across the Modbus communications link are always in INTERNAL units. The drive
itself may show the information in alternate DISPLAYED units. For Example: drive speeds are always stored
internally as tenths of a Hz but the drive may display that speed in whole Hz by dropping the tenth using
programmed conversion factors. Table 3 lists examples of the internal units used on the SCF series.
Table 3: SCF Series Internal Units
Type Unit Example
SPEED .1Hz 60Hz = 600
TIME .1Sec 30.0Sec = 300
3.3 AC Tech Drive Registers
Registers #0 through #50: (Modbus Registers #1 to #51) Reserved for configuration and control
Registers #51 through #255 (Modbus Registers #52 to #256) Reserved for the drives’ programming
mode parameters. Programming Mode Parameters are the parameters
that can be accessed from the local keypad on the drive. There is a direct
correspondence between the SCF Drive Programming Mode Parameter
number and the AC Tech Register number (and consequently, the
Modbus register number):
AC Tech Register # = (SCF Programming Parameter #) + 50
Modbus Register # = (SCF Programming Parameter #) + 51
The entries in Table 5 are based on SCF Drive Software # 213-064 Revision 03 (Parameter Configuration =
312). If a later revision of software were to change register definitions, drive operation could be seriously
affected. This will be identified for a given drive by examining Register #50 (Parameter Configuration
Number). The number displayed at power up on drive display can also identify it. If it is not 312, writing to
any register on the drive MUST NOT BE ATTEMPTED unless your Controller has been setup to support the
new configuration.