12-2
Series 90-30 PLC Installation and Hardware Manual
–
August 2002
GFK-0356Q
12
outputs are needed. Make a list of inputs and outputs needed, separating them into four types:
Discrete Input, Discrete Output, Analog Input, Analog Output. If there are any special
requirements, such as fast response, etc., make a note of them on the page. Also, if parts of
your system are physically separated from other parts, requiring Expansion or Remote Racks,
create a separate list for each location.
When you have finished developing your I/O lists, determine how many I/O modules of each
type you need. Although the “I/O Modules” chapter in this manual contains brief descriptions,
you should refer to GFK-0898,
Series 90-30 PLC I/O Module Specifications User’s Manual
for complete details.
Additional I/O Module Selection Factors
Voltage/Current Requirements
- A wide variety of possible operating voltage and current
requirements can be met with Series 90-30 I/O modules.
Positive or Negative Logic -
The applicable type can be selected to match sink or source
signal requirements. See GFK-0898,
Series 90-30 PLC I/O Module Specifications User’s
Manual,
for details.
Isolation Requirements
- Isolated discrete I/O and relay output modules may be selected to
meet isolation requirements.
Hard Contact Requirements
- Relay output modules can be used.
Cost
- The selection of certain modules can possibly reduce the number of racks required in
your system. For example, 32-point discrete I/O modules can save rack space compared to
lower density modules.
Standardization
- Sometimes a company standardizes on particular types of modules to
simplify training or stocking of spare parts.
Response Time and Noise immunity
- In general, higher response speed is attained at the
sacrifice of some noise immunity. Therefore, if high response speed is not a requirement, it
would be better to select a slower I/O module that has higher noise immunity. However, all
I/O modules, regardless of their response time rating, have a reasonable level of noise
immunity. Note that the IC693APU305 I/O Processor Option module, with its 500µs update
time, can handle I/O signals that are too fast for the CPU to handle directly (see GFK-1028,
Series 90-30 I/O Processor Module User’s Manual
).
Step 3: Selecting Option Modules
There are several application requirements that determine Option module selection. However, note
that there are some restrictions on the maximum number of certain types of modules (Analog and
Option) that can be supported in one PLC system. See the table “Maximum Number of Modules
Per System” for data.
Interfacing with a Particular Protocol or Standard -
CCM, Ethernet, FIP, Genius, RTU,
SNP, etc.
Interfacing with GE CNC controls
- Use the IC693BEM320 and IC693BEM321 I/O
Link modules.
Distance
- Genius controller modules can communicate at distances up to 7,500 feet (2,286
meters). Serial communications using the RS-485 standard can cover up to 4,000 feet
