Nidec Unidrive M200 User Manual page 59

Safety Product Mechanical
information information installation
8.6.7 Extended data types
Standard MODBUS registers are 16bit and the standard mapping maps
a single #X.Y parameter to a single MODBUS register. To support 32 bit
data types (integer and float) the MODBUS multiple read and write
services are used to transfer a contiguous array of 16bit registers.
Slave devices typically contain a mixed set of 16 bit and 32 bit registers.
To permit the master to select the desired 16 bit or 32 bit access the top
two bits of the register address are used to indicate the selected data
type.
NOTE
The selection is applied for the whole block access.
bit 15 bit 14
TYP1 TYP0
Type select
The 2bit type field selects the data type according to the table below:
Type field Selected data
bits 15-14 type
00 INT16
01 INT32
10 Float32
11 Reserved
If a 32 bit data type is selected then the slave uses two consecutive 16
bit MODBUS registers (in 'big endian'). The master must also set the
correct 'number of 16 bit registers'.
Example, read Pr 20.021 through Pr 20.024 as 32 bit parameters using
FC03 from node 8:
Table 8-10 Master request
Byte Value
0 0x08 Slave destination node address
1 0x03 FC03 multiple read
2 0x47
Start register address Pr 20.021
(16384 + 2021 - 1) = 18404 = 0x47E4
3 0xE4
4 0x00 Number of 16bit registers to read
Pr 20.021 through Pr 20.024 is 4x32 bit registers =
5 0x08
8x16 bit registers
6 CRC LSB
7 CRC MSB
Table 8-11 Slave response
Byte Value
0 0x08 Slave destination node address
1 0x03 FC03 multiple read
Length of data (bytes) = 4x32 bit registers = 16
2 0x10
bytes
3-6 Pr 20.021 data
7-10 Pr 20.022 data
11-14 Pr 20.023 data
15-18 Pr 20.024 data
19 CRC LSB
20 CRC MSB
Reads when actual parameter type is different from selected
The slave will send the least significant word of a 32 bit parameter if that
parameter is read as part of a 16 bit access.
Unidrive M200 / M201 Control User Guide
Issue Number: 2
Electrical Getting Basic
installation started parameters
bits 0 - 13
Parameter address
X x 100+Y-1
Comments
backward compatible
IEEE754 standard
Not supported on all slaves
Description
Description
Running the NV Media
Optimization
motor Card
The slave will sign extend the least significant word if a 16 bit parameter
is accessed as a 32 bit parameter. The number of 16 bit registers must
be even during a 32 bit access.
Example, If Pr 01.028 is a 32 bit parameter with a value of 0x12345678,
Pr 01.029 is a signed 16 bit parameter with a value of 0xABCD, and
Pr 01.030 is a signed 16 bit parameter with a value of 0x0123.
Start
Read register
address
Pr 01.028 127
Pr 01.028 16511*
Pr 01.028 16511*
Pr 01.029 128
Pr 01.029 16512*
Pr 01.030 16513*
Pr 01.028
to 127
Pr 01.029
Pr 01.028
to 16511*
Pr 01.029
* Bit 14 is set to allow 32 bit access.
Writes when actual parameter type is different from
selected
The slave will allow writing a 32 bit value to a 16 bit parameter as long as
the 32 bit value is within the normal range of the 16 bit parameter.
The slave will allow a 16 bit write to a 32 bit parameter. The slave will
sign extend the written value, therefore the effective range of this type of
write will be -32768 to +32767.
Examples, if Pr 01.028 has a range of ±100000, and Pr 01.029 has a
range of ±10000.
Onboard Advanced
Diagnostics
PLC parameters
Number
of 16 bit Response
registers
Standard 16 bit
access to a 32 bit
1 0x5678 register will return
low 16 bit word of
truncated data
2 0x12345678 Full 32 bit access
Number of words
1 Exception 2 must be even for 32
bit access
Standard 16 bit
access to a 32 bit
1 0xABCD register will return
low 16 bit word of
data
32 bit access to a
16 bit register will
2 0xFFFFABCD
return 32 bit sign
extended data
32 bit access to a
16 bit register will
2 0x00000123
return 32 bit sign
extended data
Standard 16 bit
access to a 32 bit
0x5678,
2 register will return
0xABCD
low 16 bit word of
truncated data
0x12345678,
4 Full 32 bit access
0xFFFFABCD
UL Listing
Comments
59