Allen Bradley
How many digital i/os does an Allen Bradley SLC 500 PLC have?
The answer depends on the rack size selected (the available module slots) along with the type and quantity of digital I/O module that are employed. Digital I/O modules range from 4 I/O points per module to 32 I/O points per module depending on the specific type of discrete I/O applied.
The link below has more information for what is available for the Allen Bradley SLC 500.
|
|
ALLEN BRADLEY 5K POT – LINEAR TAPER -1 ” SHAFT $6.95 |
|
|
ALLEN BRADLEY 50K LINEAR POT WITH SWITCH – 2″ SHAFT $7.50 |
|
|
ALLEN BRADLEY 100K OHM POT WITH TAP @ 50K 1/2″ SHAFT $6.95 |
|
|
ALLEN BRADLEY Type J 10 Kohm – 2 Watt Potentiometer # RV4ATSD103A – w/ hardware $2.99 |
|
|
ALLEN BRADLEY Type J U-2.5-MEG Potentiometer $0.99 |
|
|
ALLEN BRADLEY 2500 OHM POT LIN. TAPER -1/4″ SHAFT $6.95 |
|
|
AB ALLEN BRADLEY VINTAGE CARBON RESISTOR 1500 OHM ( 1.5K ) 1 WATT 10% 25-pieces $14.99 |
|
|
NIB Allen Bradley 330 Ohms 5% 2W Resistors (25 ct) $50.00 |
|
|
8–USED VINTAGE ALLEN BRADLEY POTENTIOMETERS,FREE U.S. SHIPPING!!! $24.99 |
|
|
ALLEN BRADLEY 2.5K POT – LINEAR TAPER -3″ SHAFT $6.95 |
|
|
ALLEN BRADLEY 2.5 MEG – LINEAR TAPER – 1 5/8 ” SHAFT $6.95 |
|
|
ALLEN BRADLEY 2.5 MEG – LINEAR TAPER – 1 1/8 ” SHAFT $6.95 |
|
|
ALLEN BRADLEY 250 OHM LIN. TAPER POT SLOT SHAFT W/LOCK $6.95 |
|
|
ALLEN BRADLEY 250 OHM LIN TAPER POT 1 1/2″ SHAFT $6.95 |
|
|
ALLEN BRADLEY 35K POT – LINEAR TAPER – 2″ SHAFT $6.95 |
|
|
ALLEN BRADLEY 55K OHM POT LIN. TAPER -1/2″ SHAFT $6.95 |
|
|
ALLEN BRADLEY 50K OHM POT LIN. TAPER SLOT SHAFT $6.95 |
|
|
ALLEN BRADLEY 25K POT – LINEAR TAPER -1 1/2″ SHAFT $6.95 |
|
|
ALLEN BRADLEY 25K POT – LINEAR – 5/8″ SHAFT w/Lock $6.95 |
How to Troubleshoot PLC Hardware and PLC IO
The programmable logic controller, more commonly known as the PLC, plays a role in almost every automated manufacturing process. The PLC is an electronically programmable device capable of almost infinite combinations of relays, contacts, and timing circuits used to control industrial machinery of all types and sizes. It is essentially a computer designed to withstand a harsh manufacturing environment. It was designed to replace complex system of relays, cam switches, and other electromechanical circuits. The first PLC’s were introduced in the late 1970’s and they continued to grow in popularity since the day of their release.
PLC’s are produced today by numerous major manufacturers including Siemens, Allen Bradley, Koyo, Fuji, Telemecanique, and Mitsubishi as well as a host of others. The programming of the PLC is performed through proprietary software produced by the specific manufacturer. Software among PLC’s is not compatible and the logic programming, although it is very similar, has many subtle differences across the different brands. The program stored in the PLC is called the ladder logic program. Problems in the ladder program can become quite involved and that is an entirely different subject altogether. Hardware problems however, are fairly similar and can be easy to diagnose if you know a little about the particular model and it’s input and output configuration.
Hardware failure of the brain, or main processor, is rare. It can be easily diagnosed visually most often by an illuminated fault indicator on the face of the PLC. An internal power supply failure would be a possibility if the PLC screen or power indicator were not lit and the technician verified that the correct voltage is applied to the power terminals. Some PLC’s are equipped with an internal fuse which can also fail. These problems are not quite as common as a failure of an input or output terminal. The IO modules are more likely to fail due to loading problems.
Inputs and outputs are available in multiple configurations and voltages. Both AC and DC are available separately and sometimes in the same unit. These input/outputs can be both digital and analog and can be configured as a transistor output or as a dry relay contact. On both the input and output side it is critical to determine the specifications of the PLC first. Having the appropriate PLC software available at the time of troubleshooting is also necessary. The first recommendation would be to compare the illuminated inputs and outputs against the software in real time. An illuminated input not displaying properly as an energized input in the software is an indication of a failed or open input terminal. On the output side, an illuminated terminal not conducting the proper output voltage can mean one of two things, the output has failed in an open position, or an improper voltage is being applied to the common output terminal. The only way to verify this would be through the use of a multimeter set on the proper voltage scale. Overall, PLC hardware troubleshooting is not complex, yet it needs to be approached in an orderly fashion because both hardware and software are required to work in harmony for a PLC to perform its intended tasks.
About the Author
Chet is a longtime associate of Obsolete Industrial Parts, an informational site dedicated to locating obsolete industrial parts including plc hardware and io modules as well as other used obsolete parts. Their official website obsoleteindustrial.com is owned and operated by Val Marketing of Carbondale, PA.
A.M. UPDATE: Muskogee High School Honor Rolls
• 12th grade — Lindsey Marie Alexander, Brooke Ranell Allen, Destiny Nicole Anderson, Sabrina Sue Appel, Alison Suezan Barton, Elizabeth Margaret Battenfield, Vann Kingsley Beard, Devin Wayne Calaway, Sofia Lara Carbone, Jessica Dawn Cash, Matthew Douglas Church, James Alexander Coburn, Morgan Ann Crank, Deanna Nichole Davis, Catherine Ngoc Diep, Laura Beth Elliott, Bailey Erin Ewing, Collin …
