Instruction manual

6. Programming Features
111
• Function code: Command codes (See below.)
• Data: Composes a series of data by combining holding register numbers
(test codes for loop-back numbers) and their data. Data length
depends on the contents of the command.
• Error check: CRC-16 (Calculate the value by the following method.)
1. The default value at calculation of CRC-16 is normally 0. In the
MEMOBUS system, change the default to 1 (all to 16-bit).
2. Calculate CRC-16 assuming that the loop address LSB is MSB and
the last data MSB is LSB.
3. Also calculate CRC-16 for a response message from the slave and
refer it to CRC-16 in the response message.
• Read Out Holding Register Contents (03H)
Reads out the contents of the holding registers with the continuous
numbers for the specified quantity. The contents of holding register
is dividing into the upper 8 bits and the lower 8 bits. They become
the data items in response message in the order of numbers.
Func-
tion
Code
Hexa-
decimal
Function Reference Message Response Message
Minimum
(Byte)
Maximum
(Byte)
Minimum
(Byte)
Maximum
(Byte)
03H Reading holding
register contents
88737
08HLoop back test8888
10H Write in several
holding registers
11 41 8 8