Chemical Engineering December 2012 - 45

TABLE 1. SYSTEM CAPABILITIES: PROS AND CONS
Costs
Controller-based
Pros
* Low-cost or freesequencing
engine human-machine
interface
(HMI) and controller
application code
Cons
* Requires HMI software
* Requires a controller
Server-based
Pros
Includes:
* Sequencer engine
* Operator electronic work
instructions
* Materials management
* Batch campaigning
* Formulation management
* Electronic journal
* Web-based reporting
* No controller required for
manual processes
* No HMI required
Equipment requirements
Controller-based
Pros
* Does not require a
server operating
system
Robustness
Controller-based
Pros
* Recipe will continue
to run in the controller
without an HMI or
network
Cons
* Requires a controller
* Requires HMI software
Server-based
Pros
* Works with a variety of user
interfaces
* Does not require a controller
* Enables multi-controller interface
and coordination
Cons
* Recipe will continue to
run without HMI or network;
no operation view if
loss of network
* Loss of power will cause
loss of current or sequence
state
Reporting capabilities
Controller-based
Pros
* Reporting available on
some systems
Cons
* Custom reporting
required
* High cost of implementation
*
Only " Real " value type
data is captured, no
string or enumerations
Server-based
Pros
* Components detect loss of network
or server and bring recipe
and phases to held safe state
* Upon system restore, the recipes
reconstruct and recipes
continue where they left off
after operator restart
Server-based
Pros
* Comprehensive data collection
performed by batch
service
* Ability to move data to multiple
data bases
* Free predefined reports
* Interaction with historical datatracking
software provides the
ability to correlate batches
with historical trend data
(Continues on p. 44)
to be considered during the selection
of a controller- or server-based
batching solution.
A controller-based solution
Pros: Controller-based solutions typically
require no additional upfront
licensing investment beyond the human-machine
interface and a controller.
In addition, a controller-based solution
solves simple batching needs; it
allows for flexible recipe management
and enables local, single-unit supervision
and control.
Cons: Limited numbers of recipes,
steps per recipe, parameter values
and reported values per phase.
This approach typically requires
more recipe upkeep in maintaining
consistency among similar units.
A server-based solution
Pros: A server-based solution enables
maximum flexibility and can be used
from simple to the most-demanding
batch requirements. Server-based
solutions solve higher-level requirements
- such as class-based recipes,
audit/diagnostics, extensive data collection
and reporting, analysis and
optimization, equipment arbitration,
integration with manufacturing execution
(MES) and enterprise resource
planning (ERP) systems, manual
work instructions, recipe safe-keeping
and active material management -
all while supporting multi-unit coordination
across multiple controllers
if required.
Cons: Such systems require the purchase
of software silencing.
Case examples
1. Pharmaceutical manufacturer
implements new batch and sequence
management. AMPAC Fine
Chemicals (AFC), one of North America's
largest custom, small-molecule
CHEMICAL ENGINEERING WWW.CHE.COM DECEMBER 2012 43
Cons
* Higher upfront investment
due to costs of implementing
and maintaining a
server
Cons
* Requires a server operating
system to run batch service
* Requires an operating system
to run clients
Cons
* Requires the PC and the
network in order to continue
sequence
* No built-in redundancy, relies
on third party
Cons
* Requires an operating
system
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Chemical Engineering December 2012

Table of Contents for the Digital Edition of Chemical Engineering December 2012
