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About PocketPCs
With the advent of Windows CE based Pocket PC
the application areas of the same have
widened. The PocketPC are also available for
Harsh Environments and are available in the
flavours like Dust, Water and Drop proof.
Companies like Iconix, a leading player in the
automation product market, has even developed
a SCADA platform called Power Genesis which
gives HMI, Alarms and Trends functionality on
a PocketPC.
PocketPC for Information system for Pharma
Plant
The
batch production record or the batch card is a
very important report which needs to be filled
during the operation of the batch.
Basically it gives the start/stop times, the
standard times, equipments and the quantity of
various materials used during the operation.
The
BPR can act as the basis of generating further
data for analysis of the production process.
Some of the information that can be derived is
cycles time of batches, consumption of raw
materials, calculation of operation delays
etc. The use of this information can be used
to monitor shop floor productivity and
optimization of batch cycle time and
monitoring of the quality of product. The
maintenance of such BPR is also mandatory as
per regulations set for industries like Food
and Beverages and Pharma.
The
Problem
One
of the main bottlenecks in implementing the
efficient recording of BPR is that the
operators are near to actual place of
operations e.g. Reactor room etc. and the PC
based HMI can be somewhere outside in the
clean room. The cost of installing the
PC-based systems in the Operation area is also
high. Also, since the operator is looking
after multiple areas of operations the cost of
installing multiple HMIs is also high. The
other hitch is that the operators do not need
access to the complete graphics screens as
they need to work to perform simple operations
like pressing of buttons to record start/stop
of operations or viewing critical parameters
etc. Also since many operations are manual the
operator needs to enter these values in the
system. Going every time to enter these values
at the HMI system is also not feasible.
The
Solution
The
above problems can be ideally solved by use of
a Pocket PCs with a small application running
on it. The PocketPC can be connected to the
Central Server using Wireless LAN.
The
cost of a PocketPC is roughly 3 to 4 times
less than the normal HMI PCs. The application
on the pocket PC can provide simple operations
like
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a) |
Viewing of
critical process parameters like Reactor
Temperature, Pressure etc. |
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b) |
Data Entry
for Manual Parameters like Raw Material
Used or Manual Quality Checks |
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c) |
Recording
of start/stop of operations of a batch.
Even Actual start/stop (control) of
operations can be done if necessary. |
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d) |
Electronic
Validation can be integrated by using
the password that is used by the
operator to log in to the PocketPC and
can be recorded with each operation. |
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e) |
Critical
Alarms can be displayed with physical
alarm like beep/vibration. |
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f) |
Simple
graphical overviews of the production
process can be given |
The
use of PocketPC in such a way will improve the
operator efficiency in the plant floor as the
information of the process is always available
with him all the time.
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A Layman’s Guide to OPC ( OLE for Process Control )
This Article is aimed at explaining OPC
technology to people who don’t have process
automation background or can be a starter for
people who have process automation background
What is
Process Automation:-
In order to understand OPC, you may frequently
come across the following terms related to
process automation. Following are the terms
that need to be understood
1) Process:
- The manufacturing / production activity
going on in the plant / factory is called as
the process. E.g. The cement manufacturing
process, Material handling process in a mining
plant, Steel manufacturing in a Steel Plant
and so on.
2) Field
devices: - It refers to the electrical /
electronic devices like motors controls, valve
controls, pressure transmitters, temperature
sensors which interact with motors, valves and
physical sensors.
3)
PLC
/ DCS System: - An electronic system based on
microprocessor which accepts inputs, processes
them according to user defined logic and
generates outputs.
4) I/Os:
- The electronic interface cards which act as
an interface between the PLC/DCS system and
the Field.
In case of Input cards they convert the
information coming from the field in the form
of electrical signals (Voltage and Current) to
a digital form which is suitable for
processing by the PLC/DCS...
In case of Output they convert the digitized
information to electrical signals (Voltage and
Current) which control the field devices.
5) SCADA
:- (Supervisory Control and Data Acquisition).
A software system which displays data from
the PLC / DCS system and also transfers
commands for operation to the PLC/DCS system.
Advanced SCADA come with rich graphical
display capabilities and control operations,
data logging functions , support for C/VB
scripting , support for software technologies
like ActiveX , ODBC and much more.
The whole range of components starting from
field devices to the Advance SCADA systems
come under the area of Process Automation. The
whole idea is to automate the complete
manufacturing / production process to achieve
high production and quality output
Organization like Siemens, ABB , Allen Bradley
, Yokogawa,GE , Foxboro etc. are major players
in process automation industry.
Why OPC :-
The data access from the Process Automation
Systems has always been a area of concern .
Due to the proprietary nature of Hardware and
the protocols used for communication.
Additional difficulties were posed by the
variety of Hardware used which varies
considerably from manufacturer to manufacturer
and also that offered by the same
manufacturer. The manufacturers used to
provide (if any) proprietary device drivers.
Writing communication programs was extremely
complex for accessing data from a Process
Automation System. Writing of software
applications , which could link the process
data to business world was not easy . The task
of porting such software from one process
system to other was also difficult.
This is the major concern that OPC addresses.
What is OPC:-
OPC stands for OLE for Process Control. This
are a set of software standards, specified by
the OPC Foundation, in order to provide a
standard and open access to data from process
automation systems and the devices usd in it.
The OPC Foundation has about 250 major
companies as its members. This standard is
based on Microsoft ActiveX technology.
The OPC foundation has defined the concept of
OPC Server. The OPC server is a ActiveX
Server which implements a standard set of
functionalities (Also called as Interfaces) as
defined by the OPC Foundation. So every
process automation system company who wants to
expose its device data to other users
(clients) writes a OPC Server for its system .
Now any client software which understands the
ActiveX technology can access data from the
automation system through the OPC Server.
The OPC Server exposes data to the clients in
the form of OPC Items . OPC Item refers to a
unit of data in the Process Automation
System.
The Basic Services Provided by a OPC Servers
are
1 ) Browsing :- Using this service the
client can browse for the OPC Items that are
provided by the OPC servers. The OPC Servers
provide a list of items that they can provide
. Once the Items are available to the client ,
they can perform operations on the items which
in turn affect the data in the process system.
2) Data Access :- Once the item
information is available by browsing the
server the client can Read and Write values
using this information. The OPC servers
provide two modes of communication.
a) Synchronous
:- In this the client makes a explicit
call to the server for reading and writing .
The client program is locked till the server
completes the read / write operation.
b) Asynchronous
:- In this the server fires events whenever
data within the process automation system
changes. The client traps this events and uses
the values passed along with the events for
any processing it needs. During writing the
write call returns immediately and the client
program does not get locked. The server
provides additional events when the value is
actually written to the system.
The Figure Below shows a typical setup using
OPC Technology :- The data is collected by the
PLC through the I/O cards for processing. The
SCADA provides function for monitoring and
control of the Data. The system using two OPC
Servers , one provided by the PLC Manufacturer
itself and the other provided by the SCADA
manufacturer.
Application of OPC :-
Once the data us available through the OPC
server it is open to integration with other
software systems e.g. Enterprise software like
SAP, custom Reporting sofwares and MIS,
Artificial intelligence softwares for process
optimization and Data Exchange between two
different automation systems.
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