Fuji Electric ALPHA7, User Manual

Page: 561 / 662

CHAPTER 13 MODBUS RTU COMMUNICATION
13-22
Transmission Protocol
13
 Communication CONT/OUT signal
The CONT/OUT signal is divided into two types: the hardware signal (sequence I/O terminal) and the
communications signal (Modbus communications) depending on the I/O form as shown in the table
below. For the hardware CONT/OUT signals, refer to the page of the sequence monitor.
Hardware signal
Communications
signal
CONT signal CONT1-8
(8 bits) CONT9-24 (16 bits)
OUT signal OUT1-5 (5 bits) OUT6-21 (16 bits)
It is possible to write and read the CONT signals via Modbus RTU communications. In reading and
writing, the same type of signals (5 to 16 bits) are handled in a batch data.
The following shows the signal arrangement in the data. The signal turns on with the corresponding bit
“1” and off with bit “0”.
a) Communication CONT signal (CONT9 - 24)
Data 4bytes
00h
00h
CONT24 CONT23 CONT22 CONT21 CONT20 CONT19 CONT18 CONT17
CONT16 CONT15 CONT14 CONT13 CONT12 CONT11 CONT10 CONT9
b) Communication OUT signal (OUT6 - 21)
Data
4bytes
00h
00h
OUT21 OUT20 OUT19 OUT18 OUT17 OUT16 OUT15 OUT14
OUT13 OUT12 OUT11 OUT10 OUT9 OUT8 OUT7 OUT6
Relation with coil data manipulation
Manipulating CONT/OUT signals can be performed in the following two ways: a batch data operation
(FC 03h, and 10h) by specifying data addresses and individual operation per bit (FC 01h, 05h, and
0Fh) by specifying each coil address. Among these, the signal statuses will follow the latest
manipulation regardless of method of batch data operation or coil address specification for
communication CONT signals 9 to 24 to which data can be written (FC 05h, 0Fh, and 10h).