Yokogawa GC1000 Mark II Process Gas Chromatograph - Manual (Page 10)

<3. Functions>
3-1
IM 11B06E01-01E
3. Functions
ASGW has the following functions.
1. Interface to DCS through Modbus RTU Slave or Modbus TCP Server
2. Read and write data for multi-analyzers (GC1000 MarkII, ASIU)
3. Mapping analyzer data to ASGW Modbus data area
4. Alarm information
3.1 Interface to DCS
ASGW has 2 functions as an interface to DCS.
• Modbus TCP Server *
• Modbus RTU Slave (2 serial ports)
*: It requires Rev.1.01.04 or later for ASGW and Rev. 1.80 or for Stardom OS.
Modbus RTU uses two RS-232C communication ports. Both ports have the same functions. Two
communication ports can be used at the same time. Modbus RTU can be used with Modbus TCP
at the same time.
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 is accepted.
3.2 Address mapping
ASGW assembles the data from multiple analyzers and sends it to the DCS.
Max. number of analyzers connectable: 31
Function Available address for mapping Available points GC1000 address area
Coil 01001 to 09000 8000 Coil, Input relay
Input relay 11001 to 19000 8000 Input relay
Holding register 41001 to 49000 8000 Input register, Holding register
Input register 31001 to 39000 8000 Input register
When the data address of analyzers is the coil or holding register, it is only possible to write to the
specific address.
Refer to the Modbus interface table in section 3.4.
4th Edition : Nov. 22, 2011-00