YASKAWA GPD 506/P5, Техническое руководство, Страница: 30 / 66

The Message Format 6-9
The starting register number is the first register to be written to. In the command message above
the starting number is 01h, indicating that the first register is the frequency reference. A listing of
the GPD 506’s registers is shown in Chapter 7, Registers.
The quantity indicates how many consecutive registers are to be written to. The quantity may range
from 1 to 8 registers. If the quantity is greater than 8, an error code of ‘3’ is returned in the fault
response message. In this command message there is two consecutive registers to be written to:
001h-Operation Command and 002h- Frequency Reference.
The number of data bytes is the number of bytes of data to be written to the drive. The number of
data bytes is actually the quantity multiplied by 2, since there are two bytes of data in each
register.
The data section of the response message contains 8 upper and 8 lower bits of data for each
register that is being written to.
A CRC-16 value is generated from a calculation using the values of the address, function code,
starting register number, quantity, number of data bytes, and data sections of the message. The
procedure for calculating a CRC-16 is described at the end of this chapter. When the slave receives
the command message, it calculates a CRC-16 value and compares it to the one in CRC-16 field of
the command message. If these two CRC-16 values are the same the slave has received the proper
command message. If these two CRC-16 values are not the same the slave does not respond.
If the command message has a valid slave address, function code, starting register number,
quantity, number of data bytes, and data values, the slave will respond with a normal response
message. If the command message has an invalid slave address, function code, starting register
number, quantity, number of data bytes, and/or data values the slave will respond with a fault
response message.
Normal Response Message
The normal response message contains the same slave address and function code as the
command message, indicating to the master what slave is responding and to what type of function
it is responding.
The starting number is the first register that was written to. In the response message above the
starting number is 01h, indicating that the first register is the operation command.
QTY.
02h
SLAVE ADDRESS
FUNCTION CODE
03h
00h
20h
00h
04h
45h
F0h
START-
ING
REGISTER
NO.
CRC-16
UPPER
LOWER
UPPER
LOWER
LOWER
UPPER