Glossary Of Terms - Teledyne 2105 Installation And Operation Manual

2105 Interface Module
Section 5 Modbus Protocol and 2100 Output

5.4 Glossary of Terms

5-4
The operation sequence for the example above can be summa-
rized in the following steps:
2150:
1. 2150s take readings from probes.
2. 2150s store readings (level, velocity, flow rate, etc.) in their
specified registers.
Process Control:
3. The user requests data through Process Control.
4. Process Control asks the OPC server to gather informa-
tion.
5. OPC connects to the 2150 stack through the cable (direct
connection), takes register data from the specified 2150,
and populates the OPC server's holding index.
6. Process Control takes data from the OPC server's holding
index and gives data to the user.
Note that Process Control can be either manual or automated in
this example, and that the OPC server and Process Control may
be located physically on the same computer.
ASCII – Short for American Standard Code for Information
Interchange, ASCII is a code that represents English characters
with numbers. Most computers represent text with ASCII code,
making it possible for one computer or device to share data with
another. For output, 2100 modules support Modbus ASCII pro-
tocol.
Dedicated Line – A telecommunications path reserved for com-
munication between two specified points and not shared among
multiple points.
Modbus Protocol – Modbus Protocol is a messaging structure
used to establish master-slave/client server communications
b e t w e e n i n t e l l i g e n t d e v i c e s . M o d b u s i s a s i m p l e
command/response mechanism to read from and write to reg-
isters.
OPC – OPC (OLE for Process Control) means open connectivity
via open (free for use) standards. It is a series of software stan-
dards specifications that fill a need in automation (like printer
drivers did for Windows), acting as a translator for data trans-
mission and process control.
The specification defines a standard set of objects, interfaces, and
methods for use in process control and manufacturing auto-
mation applications to facilitate interoperability. There are hun-
dreds of OPC Data Access servers and clients.
Registers – Registers are locations in memory that have specific
data stored for retrieval or are used for control functions. A reg-
ister is a holding place for a piece of digital information within
the equipment. The definition of what is contained and where
(the registry number, or address) is decided by the manufacturer
(in this case Teledyne Isco).