8
P94MOD01B
Note that all parameters in the PositionServo drive are 32 bit values and they cannot be accessed by Write
Single Register functions or Read Holding Register functions with a length of 1 (one 16 bit register). The
user has to use two 16 bit registers to read/write one 32 bit register and for this purpose should reserve 2
consecutive addresses per 32 bit register.
31
Discrete Number
17 16
0
30
ModBus Discrete Number and 32-bit Format
14
1
15
Bit
29 28 27 26 25 24 23 22 21 20 19 18
13 12 11 10 9 8 7 6 5 4 3 2
16
2
15
1
3 4 5 6 7 8 9 10 11 12 13 14
Hex value
x0001
x4000
x0002
x8000
x2000 x1000 x0800 x0400 x0200 x0100 x0080 x0040 x0020 x0010 x0008 x0004
Figure 1: 32 bit Pack Format Discrete Data
The user doesn’t have any discrete functions but can use holding registers with DWORD (integer 32 bit) access
to write discrete values.
When the PositionServo drive receives a Modbus message, the requested function is executed and the drive
can reply with a ‘Normal’ message, an ‘Exception’ Message or a ‘No’ message. These messages are described
in the Modbus Application Protocol Specification V1.1.
The PositionServo drive also supports a Modbus broadcast address. In this case the PositionServo drive receives
a correct Modbus request and executes it without sending any reply back.
The DWORD (double word) and FLOAT numbers are sent with the LOW WORD FIRST convention by the
PositionServo drive.
15
Register_L (Bits 15 ... 0)
1 0
16
14
DWORD_ Unsigned Single Precision 32-bit Format
Register_H (Bits 31... 16)
30
17
31
HByte
HByte
LByte
LByte
13 12 11 10 9
15
8 7 6 5 4 3 2
29 28 27 26 25 24 23 22 21 20 19 18
Figure 2: DWORD Format
31
1bit
sign
8 bits
exponent
23 bits
mantissa
23 22
0
30
IEEE 754 Floating Point: Single Precision 32-bit Format
Figure 3: FLOAT Format
Note:
Some terminals may have to be configured appropriately in order to accept such a WORD order.
