Micromod RetroPAK: SLC Configuration Manual - Manual (Page 10)

Command Series Migration to MOD 30ML
Function Codes – Introduction
The user database is configurable and writable to make the instrument perform a variety of
executable functions. The basic logical element of the database is a function block.
Function blocks are grouped to form multiple process loops. Loops in turn are grouped
into sets that are scanned (executed) at the same rate. Up to five different scan rates can be
configured through the interface block. The instrument operates at a fixed base rate (50
milliseconds) and each of the five groups can be configured at any multiple of the base
rate up to the maximum time value (about 1193 hours). I/O module blocks define the
physical interface to the database and serve as data handling blocks between the process
and the function blocks.
The MOD 30ML has a wide variety of function blocks with which you can configure any
complex control strategy. There are 4 types of configuration blocks in the MOD 30ML /
Modcell database. They are:
1. Environment Blocks
2. I/O Module blocks
3. Function Blocks
4. System Blocks
Environment Blocks:
The environment blocks support general instrument operation and do not directly perform
the user defined control functions. These blocks always exist as part of any configuration.
Some of the functions that are executed by these blocks are similar to that of the Station
type blocks in the CLC/SLC world.
The default database contains the following 4 blocks. (In the case of Modcell, the default
database contains only 2 blocks namely the IF and SE).
Interface block (IF):
The interface block contains the overall instrument related information and functionality.
Up to five scan intervals can be specified in this block. The function blocks in the database
can be grouped in to loop compounds and each loop compound can be assigned a scan rate
from this group of five scan rates. The function blocks will be executed at the assigned
rate in the instrument RUN state.
This block also has configurable parameters for start-up options such as running on I/O
mismatch and start-up types such as warm and cold starts. This block also has parameters
that are used for enabling or disabling certain diagnostics.
System Event Block (SE): The system event block supports general instrument operation.
This block defines diagnostic and system event acknowledgement and reporting
capabilities. System events occur in the instrument, are reported by database blocks, and
can be stored into the system event queue. The different types of system events are:
Informational only, Process Alarms, Notification/Request Messages, Diagnostics and
Acknowledge Only Diagnostics.
The system event queue stores a configurable number of time stamped event codes for the
diagnostic points and events reported by the database blocks. These codes are translated
into messages for operator display or logging by the interface software.
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