Varec 8300 series, Инструкция по установке и эксплуатации, Страница: 60 / 150

Tank Gate Interface
50 Installation and Operations Manual
5.2.2 Application
The DAU point provides an interface to Saab Data Acquisition Units (DAU) via an FCU, using a
8203 Dual RS-485 Communications Interface Module or the 8212 Saab (TRL/2)
Communications Interface Module.
If the Data Acquisition Units are connected to a Saab FCU, then an 8203 Dual RS-485
Communications Interface Module or the 8212 Saab (TRL/2) Communications Interface Module
is used to read data. The 8203 Dual RS-485 Communications Interface Module or the 8212 Saab
(TRL/2) Communications Interface Module automatically detects startup, and an MSCAN point
is automatically created to manage the scanning task. Chan determines which Channel is used
for communications to the slave device. The Chan parameter must match the channel used to
communicate with the Saab DAU.
A DAU point is needed for each DAU connected to the 8303 TGI or the 8212 Saab (TRL/2)
Communications Interface Module. The ID must match the unit address of the Saab DAU. The
BaudRate and ComParams values must match the communications parameters of the Data
Acquisition Unit. The communications parameters are set as each DAU point is processed.
8203 TGI or the 8212 Saab (TRL/2) Communications Interface Module software points may
begin scanning when the point is created, or when the correct Channel number is assigned.
Which of these events begins the scanning process varies with each point.
The DAU point works in conjunction with the Modbus Master protocol handler (MSCAN). MSCAN
points are automatically created so you only have to set the Chan, BaudRate, ComParams and ID
parameters in order to establish communications with the Saab DAU.
The Mode parameter determines whether the DAU point reads the data from the Saab FCU’s
holding registers. If the Mode is 0x02, then the data is read from the holding registers. The Addr
parameter determines the FCU address and the ID is not used. If the Mode is 0, then the FCU
sends the request to the DAU and sends the response back to the 8303 TGI or the 8212 Saab
(TRL/2) Communications Interface Module. The ID is used and the Addr parameter is ignored.
This mode is sometimes referred to as “pass-through’ mode.