DEFINITIONS

Address

An address within the PLC refers to a specific location within the PLC program. The FA-2J PLC CPU will support a total of 3300 Words of Memory. These addresses range from 0 to 3299. Addresses can also refer to the assigned Internal Relay, I/O, Timer, Counter, and Data Register location in a PLC program.

Analog

Variable voltage or current signal used to measure a changing variable such as Temperature or Humidity.

Analog Input Module

This is the 4 to 20 milliamp module that reads the current signal from the Temperature/Humidity Sensor. The Analog Input Module is an 8-bit binary that provides a binary value to the PLC that is between 0 and 255. The 4 to 20 milliamp signal is converted to 256 individual setpoints with the minimum value of 4 milliamps equal to 0 and 20 milliamps equal to 255.

Binary

Binary is a software term that refers to bits that are addressed as 1, 2, 4, 8, 16, 32, 64, 128, etc. The sum of all of the bit switches that are on is an integer value with a specified range. The most common are 0 to 255, 0 to 4095, and 0 to 65535.

Bit

A bit is a single address point in a PLC program. These can be individual Inputs, Outputs, or Internal Relays. Bits usually refer to individual Internal Relays. The terms 8-Bit or 12-Bit refer to analog resolution. An 8-Bit analog signal is a binary integer value that is separated into 256 setpoints. There are a total of 8 binary switches, 1, 2, 4, 8, 16, 32, 64, and 128, the sum of these are read by the PLC as a single value from 0 to 255. A 12-Bit analog signal has 4096 setpoints and has a binary value with a range of 0 to 4095.

CEC

Controlled Environmental Cabinet - Telecommunications Site that is partially below ground.

CEV

Controlled Environmental Vault - Underground Telecommunications Site

Counters

The PLC contains 46 internal counters that count pulse signals. Counters are used as timers throughout the PLC program by counting one-second pulses. The PLC Timers have a timing range of 0.1 to 999.9 Seconds, which is a maximum of approximately 16 1/2 minutes. Counters have a range of 0 to 9999. Counters used as timers in the PLC program can count for much longer than timers since they are used to count one second pulses, i.e. 3600 seconds equals one hour. Counters are also used in the program to record the quantity of Alarms for data logging purposes.

CPU

Central Processor Unit - The brains of the Idec PLC

Data Logging

Storage of values within the PLC for historical trending and troubleshooting. The Temperature Data Log consists of Data Registers 1500 to 1589. Humidity uses Data Registers 1600 to 1689. The Elapsed Hour Meters for load running time are stored in Data Registers 1700 to 1769. D.R. 1770 to 1789 are used for PLC Diagnostics. Counters are used to store the quantity of alarms that have occurred.

Data Register
Numeric Storage location within the PLC for Temperature/Humidity Readings, HVAC Load Setpoints, Load Elapsed Hour Meters, PLC Program Calculations, Temperature/Humidity Data Logging, etc. Data Registers are numbered from 800 to 899 and 1500 to 1799 (Data Logging D.R.).

Deenergize

The PLC turns a load off.

EEPROM

Electrically Erasable Programmable Read Only Memory - This type of memory storage is "burned" into a memory storage chip that does not require a battery to retain the memory. The chip can be repeatedly reprogrammed using the appropriate PROM Burner. Idec's Hand Held Program Loader/PROM Burner, PF2-2H4RE-CBL, is used to "burn" the EEPROM Memory Packs, PFA-1M14U.

Energize

The PLC turns a load on.

Expansion Backplate

The black metal plate that the PLC I/O modules mount on, Part Number PFJ-EB1. The FA-2J CPU includes a backplate that supports the first two modules.

Input

Control signal connected to the PLC 24 Volt D.C. Input Module (Green labeled module PFJ-N162U) such as a switch or pushbutton.

Integral Fan

HVAC Fan that is energized with the Air Conditioner and/or Heater

I/O Input/Output

This refers to the PLC Input and/or Output Modules or addresses.

I.R. Internal Relays

These are logic programming addresses within the PLC that are similar to electromechanical relays except there is no limit (except PLC Memory) to how many contacts that can be referenced to each coil. The number range of these addresses is 400 to 697, 2201 to 2357, and 2400 to 2697.

LED

Light Emitting Diode IDEC's PLC uses RED LEDs for all I/O points, POWER and RUN Indication, and for an ERROR Condition.

Memory

Memory is the amount of program addresses that the PLC will hold. Each contact and coil within the program uses one word of memory. Timer and Counter coils each use two words of memory. The PLC Calculation command, F 147 or F 247, each use two words of memory. The FA-2J PLC CPU will support up to 3300 words of memory which is stored in the Memory Pack.

Memory Pack

The Blue labeled plug-in module, PFA-1M14U, located at the bottom of the Idec FA-2J PLC CPU. This holds the PLC program in EEPROM memory, which is retained without the need for a battery. These are replaceable for approximately $86.00 and will be shipped pre-programmed with the latest program version if the type of program is specified when the order is placed, i.e. ATTNJ1, CEV24, CEV10, NJ2AC1, etc.

Octal Based Numbering System

The PLC I/O and Internal Relays can only end in a numeric address from 0 to 7. There is no 8 or 9 used as the last digit. Inputs begin their numbers from 0 to 7 and the next group of eight is 10 to 17. Outputs begin numbering from 200 to 207 and the next group of eight is 210 to 217. Internal Relays begin numbering from 400 to 407 and the next group of eight is 410 to 417.

Output

Control signal from the PLC Plug-in Relay Output Module (Red labeled module, PFJ-T081U) controlling HVAC Loads, Alarms, etc.

P.B.

Abbreviation for Pushbutton

PLC

IDEC FA-2J Programmable Logic Controller located inside control panel. This controls all of the loads and alarms in a CEC, CEV or a Hut.

Program Mode

The PLC's RUN LED is off and the PLC program is not executed. All PLC outputs are off.

Run Mode

The PLC's RUN LED is on. The program is continuously scanned and the outputs are updated every 10 - 15 milliseconds depending on the scan time.

Scan Time

The amount of time the PLC takes to complete a single pass of the program solving the required program logic along the way. These programs have a scan time between 10 and 15 milliseconds.

Special Internal Relays

These are predefined by Idec to perform specific functions such as internal pulse signals, PLC in RUN Mode Bit, PLC Program Mode Control, First Scan of the PLC Bit, etc. These are addressed from 700 to 717.

Timers

Timers are incorporated into the PLC CPU to provide delays for certain required logic. There are a total of 80 Timers with addresses that range from 0 to 79. These Timers have a range of 0.1 to 999.9 Seconds, which is a timing resolution of 0.1 Seconds or 100 milliseconds. The FA-2J CPU also offers an additional 80 timers with addresses from 1100 to 1179 with a timing range of .01 to 99.99 seconds which is 10 millisecond timing resolution. The high-speed timers are not presently being used in the CEC/CEV/Hut programs.