Rack Location For The Bus Interface Module - GE 90*-30 PLC Series User Manual

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Rack Location for the Bus Interface Module

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The LBIM can be located in any rack in any slot (except for the slots in the main rack that are
reserved for the power supply and CPU) in a Series 90-30 PLC. For the most efficient system
operation, the main baseplate is preferred.
The following slots are reserved in the PLC main rack:
Models 331, 340, 341, 351, 352 and later: Slot 0 reserved for power supply
Models 311 and 313:
To estimate whether the system you want to design is possible, complete steps 1–3, below.
1. The I/O configuration block uses a base of 90 bytes of user memory. Each smart module uses
257 bytes of user memory for parameter data. Finally, every I/O segment uses an additional
40 bytes of user memory.
Example of segments:
A discrete input module has one segment (%I).
2. The total user memory required by a configuration is the sum of all these parts:
base configuration size (90)
+ number of smart modules *257
+ number of segments *40
= total user memory required for the configuration
3. The total user memory available for configuration varies with CPU model. If the number
derived from the formula above is greater than the number next to the CPU that you are
using, the system will not work due to memory limitations.
CPU
311
313
323
331
340/341
351/352
Series 90™-30 PLC LONWORKS® Bus Interface Module User's Manual – June 1997
Slot 1 reserved for CPU
Slot 0 reserved for power supply (The CPU is built into the
baseplate.)
Available Memory
(bytes)
4,720
4,720
4,720
4,656
8,176
16,368
GFK-1322A