Instruction Manual

<3. Functions>
3-2
IM 11B06F01-01E
3.2 Alarm information
ASIU checks the status of I/O and power card, and the following alarm information is provided on
Modbus interface as Boolean data.
Main power failure, 24 V DC power failure, I/O module failure
3.3 Modbus interface table
ASIU has the function of Modbus TCP Server and Modbus RTU slave at the same time, and
indicate DI, DO, AI and the alarm information on the specic address by mapping. The writing
command to DO is also set on the specic address by Modbus interface.
Modbus interface table
Function Function
Code
BIT/WORD Maximumdatabyaccessinone
communication packet.
Read coil status 1 (0x01) BIT 2000 bits
Read input relay status 2 (0x02) BIT 2000 bits
Read holding registers 3 (0x03) WORD 125 words
Read input registers 4 (0x04) WORD 125 words
Write coil 5 (0x05) BIT 1 bit
Write single register 6 (0x06) WORD 1 word
Loopback test 8 (0x08) WORD 1 word
Write multiple coils 15 (0x0F) BIT 800 bits
Write multiple registers 16 (0x10) WORD 100 words
Read device ID * 43 (0x2B) ASCII string
*: Device ID consists of vendor, product code and revision number.
Vendor : “YOKOGAWA”
Product: ”ASIU”
REVISION: “1.01.01” (example)
l MaxnumberofClient
When Modbus TCP Server is used, up to 4 clients (DCS) can be connected at the same time.
When the multiple clients request the same command, the last requested command in the action
internval of ASIU is accepted.
l Update Interval
The Modbus data is updated every 100 msec for DI, DO, AI and all alarm information.
l Serial Port
RS-232C COM port on CPU card is used for Modbus RTU.
l Monitoring Time
When there is no command from a client as a Modbus TCP server within 30 sec, the communica-
tion is cut off.
4th Edition : Nov. 22, 2011-00