Use the extended-local I/O link when you need I/O updates more quickly than is possible from remote I/O link. A local I/O link offers faster update time and scan than a remote I/O link. The extended-local I/O link is limited to 30.5 cable-m (100 cable-ft). The distance between controller and chassis of I/O can not be put more than 30.5 m, otherwise you have to use an I/O link remote.
The controller of PLC-5/40L or PLC-5/60L and the local adapter of I/O module for 1771-ALX create the extended local I/O link. You can delete a module adapter from a chassis on the local I/O link because of the cabling design without disturbing communication to other chassis on the extended-local I/O link.
Selecting I/O Modules
Select I/O modules to interface your PLC-5 controller with machines or processes that you choose while analyzing the operation of your plant. Use the following list and table as guidelines for selecting I/O modules and operator control interfaces.
• How much I/O is required to control your processes?
• Where will you concern to I/O points for portions of an entire process
• When the process is spread out over a large physical area?
• What type of I/O is required to control your processes?
• What is the required voltage range for each I/O module?
• What is the backplane of current required for each I/O module?
• What are the distance and noise limitations for each I/O module?
• What isolation is required for each I/O module?
Guidelines for Selecting I/O Modules
Choose this Type of I/O Module: Discrete input module and block I/O module
Types of Field Devices or Operations: Many kinds of selector and contact switches, and also relay and breakers.
Explanation: Modules sense input opened/closed or on/off signals. The signals of discrete involve ac or dc.
Choose this Type of I/O Module: Discrete output module and block I/O module
Types of Field Devices or Operations: lights, alarms, horns, fans, valves, control relays, solenoids or motor starter.
Explanation: signals module output of interface with opened/closed or on/off devices. The signals of discrete involve ac or dc.
Choose this Type of I/O Module: Analog Input module
Types of Field Devices or Operations: Many kinds of transducers.
Explanation: Change the signals analog to the input values of PLC controller.
Choose this Type of I/O Module: Analog Output module
Types of Field Devices or Operations: actuators, chart recorders, analog meters, motor drives, valves.
Explanation: Interpret PLC controller output to analog signals for field devices.
Choose this Type of I/O Module: Specialty I/O modules
Types of Field Devices or Operations: EMany kinds of encoders for communication, tag readers, weigh scales, bar-code readers, display devices.
Explanation: Are generally used for specific applications such as position control, PID, and external device communication.
Selecting I/O Module Density
The density of an I/O module is the number of controller input or output image-table bits to which it corresponds.
Use these guidelines for selecting I/O module density:
I/O module 8-point
• Presently it is using 8-point modules
• It requires integral, fused outputs separately
• cost down per module
I/O module 16-point
• Presently it is using 16-point modules
• It requires a special wiring arm of outputs fused separately
I/O module 32-point
• Presently it is using 32-point modules
• minimize modules number
• minimize the chassis I/O space requirement
• cost down per I/O point
Place I/O modules in a chassis depending on the electrical characteristics of the module. The placement is made left to right, with the left-most position being closest in the chassis to the PLC-5 controller or the I/O adapter module.
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Allen Bradley PLC
Allen Bradley PLC