Category Archives: PLC Applications

PLC vs. DCS: What’s the difference?

Before we get into the differences of a PLC’s and DCS’s, we need to talk about what each of them are designed to do.

What is a PLC?

A PLC, or Programmable Logic Controller, is a computer that has been adapted to specifically meet the needs of any specific manufacturing process. These devices come in many different shapes and sizes, with many options for digital and analog I/O, as well as protection from high temperatures, vibration, and electrical noise. The invention of the PLC allowed computers to be streamlined into the industrial automation process.

A PLC can be a single device calculating and executing operations, or a rack of different modules may be used to meet whatever your automation system requires. Some of the additional components include processors, power supplies, additional IO, interfaces, and much more.  Every part works together to be able to run open or closed loop operations that are rated at high speed and high precision. Take a CNC machine for example; a PLC would be used to control positioning and motion, as well as torque control. These devices are popular because they are very inexpensive relative to the amount of power and how many hours you get out of them.

 What is a DCS?

A Distributed Control System is an automated control system that streamlines the functionalities of the various devices that are used throughout an entire work space. This type of system uses many different controllers to allow all the machining parts to talk to each other as well as computers that can input parameters and display information such as power usage, speed, and much more. These controllers are distributed geographically across a plant to allow for high-speed communication to the control room. When using different types of modules however, the system may require different communication standards such as Modbus and Profibus. DCS’s started coming to fruition throughout the 1960’s once the microcomputer was brought widespread into the market.

Then what exactly is the difference?

A PLC will probably be used to control a machine that isn’t too complex wheres the DCS can have total control of all the operations in an entire plant. The PLC is preferred in situations where the machine does not have to worry about meeting specific conditions inside the plant. These conditions typically involve operations that may need to stop or restart, as well maintaining precise temperatures. A DCS will be able to take advantage of all the aspects of an automated system, from the machines and sensors to the controllers and computers. An entire DCS is much more expensive than a few PLC’s, but each have their advantages in any given situation and certain automated systems will always require one over the other.

Visit MRO Electric and Supply’s website to see all of our available Programmable Logic Controllers. If we don’t have what you need listed on the site, contact us at sales@mroelectric.com or (800)691-8511 and we will be happy to help.

PLC Security

plc security

PLC Security

Programmable logic controllers, also known as PLCs, initially came about in the late 1960s. PLCs were designed to replace relay-based machine control systems in the major U.S. vehicle manufacturing space. The relay-based control systems were considered hard to use and were disliked amongst those in the automation and manufacturing in.

In 1968, Dick Morley of Bedford Associates in Massachusetts designed the Modular Digital Controller, later dubbed the Modicon. After the Modicon 084’s initiation into the world, there was no looking back to those relay-based control systems. Be sure to check out our article covering Modicon PLC history to learn more.

PLCs are user-friendly microprocessor-based specialty computers that carry out control functions, many of which are of high levels of complexity. They are engineered to endure harsh and strenuous situations such as in heated, cooled and even moist environments. Used for automation usually in the industrial electromechanical space, PLCs are computers that deal with the controlling of machinery, often on  the following:

  • factory assembly lines
  • power stations
  • distribution systems
  • power generation systems
  • gas turbines,

PLCs are programmed using a computer language. Written on a computer, the program is then downloaded to the PLC via a cable. These programs are stored in the PLCs memory. The hard-wired logic is exchanged for the program fed by its user during the transition between relay controls to PLC. The manufacturing and process control industries have gotten to take advantage of PLC applications-oriented software since Modicon PLCs inception.

plc security
PLC Functions and Directions

PLCs use programmable memory in order to store particular functions and directions. Some functions and directions would include:

  • on control
  • off control
  • timing
  • sequencing
  • counting
  • arithmetic
  • data manipulation
PLC Types

Understanding the different types of PLCs will be very helpful when looking into PLC security.

The numerous types of PLCs can be organized into three principal categories:

  • Advanced PLC: Advanced PLCs offer the greatest processing power out of all of the PLC types. They feature a larger memory capacity, higher input/output (I/O) expandability, and greater networking options.
  • Compact Controller: Logic Controllers are increased intermediate level offerings with an increased set of instructions and a greater input/output (I/O) than a run-of-the-mill logic controller
  • Logic Controler: A logic controller is often referred to as a ‘smart relay’. They are generally straightforward to use and considered a good place to begin when becoming acquainted with PLCs. They are cost-effective for low input/output (I/O), slower speed applications.
PLC Security

As security concerns remain in many professional spaces including the factory automation space, becoming up-to-speed with the different types of PLC Security is imperative. By creating and implementing an effective strategy to remain secure, you will likely avoid issues, downtime, and setbacks. Understanding the different types of PLCs will be very helpful when looking into PLC security.

PLC Cybersecurity: How the control network is linked to the internet, as well as other networks. A handful of PLC issues could likely involve the following:

  • Incident response planning and plans;
  • Issues drafting and reviewing policies
  • Issues drafting and reviewing procedures
  • Retention of cybersecurity experts and vendors;
  • A need for preparation of a breach:
    • exercises
    • training
    • breach simulations
  • A need for cybersecurity insurance review and counseling
  • A demand for record management and information infrastructure;
  • Privacy risk management
  • Assessment of cybersecurity risk in mergers and acquisitions;
  • Payment Credit Industry (PCI) Compliance protocols
  • Vendor contract management protocols
  • Supply chain risk management

 

PLC Physical Security: Although PLC physical security differs from PLC cybersecurity, it is still important and should be prioritized when an individual or a company is undergoing breach simulations, training, and exercises. PLC physical security deals with:

  • correcting default passwords
  • ensuring only certified individuals are in the control system’s environment
  • limiting access to thumb drives and securing access

MRO Electric and Supply maintains a comprehensive stock of Modicon PLC parts, including the Modicon Quantum series. Also, feel free to check out our repair and core exchange programs to learn how to save.

Understanding Issues with Security
In order to create and implement training and procedures for staff, you must understand how issues with security occur.  Not all cybersecurity attacks occur from external hackers or scammers. In fact, experts believe that only an estimated 20% of all cybersecurity attacks are intentional and intended to be malicious. Whether you think it’s possible or not, an offended employee could indeed be your hacker. Almost always caused by software issues, device issues, and malware infections, cybersecurity seems straight-forward initially, until you dig into those fine, often overlooked details.

As many in the automation space may know, PLC cybersecurity wasn’t a thing a decade ago. These days, PLCs are connected to business systems through any run-of-the-mill network and aren’t separated from other networks that other automation equipment may also be on.  As time goes on, it’s becoming more and more common to see TCP/IP networking from a business system standpoint. By connecting via TCP/IP, data exchange, as well as more rational and scalable business decisions, is enabled.

PLC Security Factors:
  • Although it may not actually connect to the internet, a control system is unsafe. Contrary to popular belief, a modem connection could also experience intrusion and a hack.
  • Wireless networks, laptop computers, and trusted vendor connections could be other sources of connections in which people may be likely to overlook.
  • Keep in mind that the majority of IT departments are unaware of factory automation equipment, including CNCs, CPUs, PCBs, robotics parts and, last but not least, PLCs.
  • Piggybacking off of the last point, IT departments’ lack of experience with the aforementioned equipment, along with their lack of experience with industrial standards and scalable processes indicate that they should not be in-charge and responsible for a company’s PLC security. Nobody wants an annoyed employee to make inappropriate changes to a PLC’s communication highway.
  • Hackers do not necessarily need to understand PLC or SCADA to block PC-to-PLC communication. They absolutely do not need to understand a PLC or SCADA system to cause operational or programming issues.
  •  Often times, control systems, including ones that many PLCs integrate with, use Microsoft Windows, which is very popular amongst hackers.
  • Some PLCs crash simply by pinging an IP address, like what happened at the Brown’s Ferry Nuclear Plant, which is located in upstate Alabama. Since the incident in 2006, the plant has undergone numerous security, operational, and management improvements.

 

In conclusion, when a security breach occurs, regardless of the specifics, understanding that time is of the essence will help smooth over most incidents. Trusting who has access to a control systems environment and thumb drive is crucial. If someone has access to the control system environment and thumb drive, ensure they’re well-qualified and up-to-speed with their team and/or company.

 

 

Modicon PLC History

Modicon PLC History

Modicon PLC History

 

Richard E. Morley, also known as Dick, was an American electrical engineer. He was an employee at Bedford and Associates, located in Massachusetts. He is most commonly known for his involvement with the production of the first Programmable Logic Controller (PLC) for General Motors and the Modicon in 1968. General Motors Company, often referred to as GM, is an American multinational corporation that is headquartered in Detroit, Michigan that engineers, manufactures, markets and distributes vehicles and vehicle parts and sells financial services.

Known as an author, educator, influencer and specialized engineer, Morleys’ accomplishments and contributions have earned him numerous awards from families such as ISA (the instrumentation systems and automation society), Inc. Magazine, Franklin Institute, SME (the Society of Manufacturing Engineers), and the Engineering Society of Detroit. SME offers the Richard E. Morley Outstanding Young Manufacturing Engineer Award for outstanding technical accomplishments in the manufacturing space by engineers age 35 and younger.

Schneider Electric currently owns the Modicon brand of PLCs. The PLC has been recognized as a major advancement in the automation space and has had an unprecedented impact on the manufacturing community as a whole. PLCs were designed to replace re-wiring and hard-wired control panels with software program changes when production updates were necessary. Before PLCs came about, several relays, drum sequencers, cam timers and closed-loop controllers were used to manufacture vehicles and vehicle parts. Re-wiring the relays and other necessary components was a very in-depth and costly process, but clearly worth the effort. The Modicon 084 PLC was modeled to be programmed in ‘ladder logic’ which had the look of the schematic diagrams of relay logic it was replacing.  This made the transition to PLCs easier for engineers and other professionals in the manufacturing space.  The automotive industry is still one of, if not the largest users of PLCs today. MRO Electric and Supply has new and refurbished Modicon parts available including the Modicon Quantum series. We also offer repair pricing. For more information, please call 800-691-8511 or email sales@mroelectric.com.

The Modicon PLC Timeline

A few years later, in the 1970’s, dialogue between PLCs came about. Introduced as the first industrial communications network, Modbus was based on a Slave/Master architecture that used messaging to communicate between Modbus nodes. All and all, a lacking standardization made PLC communications a nightmare.

In the  1980’s, General Electric made an effort to regiment the interconnection of devices from several manufacturers with MAP (manufacturing automation protocol). PLC programming software was also created to operate on personal as well as professional computers in order to remove the need for dedicated programming terminals or handheld programmers.

As years have gone on, PLCs have evolved as technology evolves. Nowadays, they include process, motion, and distributed control systems, as well as complex networking. Equivalent to an average, run-of-the-mill desktop computer, PLCs have capacities for data handling storage and impressive processing power.

 

plc

How to maintain a PLC (Programmable Logic Controller)

How to maintain a PLC (Programmable Logic Controller)

As many of us know, PLCs (programmable logic controllers) are staples in the factory automation world. In order to have them running optimally and as efficiently as possible, routine maintenance is imperative. Generally, manufacturers produce PLCs to endure strenuous, unsterilized environments. By adhering to an adequate maintenance schedule, PLCs operating timeframe can be lengthened.

Protect your PLC

Always be on the lookout for corrosive and conductive contaminants that have the potential to become a detriment to a PLCs’ components. By completing visual inspections for black dust and blowing airborne particles from the PLC’s vicinity, you are lowering the likelihood of contamination.

Is power flowing?

A PLC will not operate correctly without adequate power. To avoid any operation bugs, remain vigilant of any surges or shorts.

Calibrate Analog Components

Always refer to the preventative maintenance schedule for any analog input device. Analog inputs need to be cleaned regularly and calibrated as accurately as possible.

 

Take EMI into consideration

EMI (electromagnetic interference) is known to cause horrible issues for PLCs without clearly indicating what the specific issue is or how to go about fixing it. To remain ahead of the game, many perform an audit of the local wiring to pinpoint potential EMI sources before they interfere with the operation of your PLC. Lower-level components and high-current wires often interfere with each other, which wiring designs must take into consideration.

Additional PLC Maintenance Tips

By creating a PLC maintenance checklist and adhering to it strictly, operating errors can likely be avoided. The space between the PLC and the machine it’s controlling should be minimal.

MRO Electric and Supply has new and refurbished Modicon PLC parts available here. We also offer repair pricing. For more information, please call 800-691-8511 or email sales@mroelectric.com.

 

Modicon 140AVI03000

Modicon Quantum 140AVI03000 – Product Spotlight

The 140AVI03000 is a Analog Mixed Current/Voltage Input Modules that is part of the Modicon Quantum series. This Analog In 8 Channel Bipolar Modules accepts a mix of current and voltage inputs. Jumpers are required between the input and sense terminals for current inputs. The 140-AVI-030-00 contains a total of 18 LEDs. The “Active” LED remains on and green when Bus communication is currently present. The “F” indicator will light up red when an error external to the module has been detected. The green LEDs 1 through 8 will turn on when the indicated point or channel is ON. The red 1 through 8 LEDs when light up for two reasons. Either the indicated channel is out of range (1 – 5 Volts), or a broken wire condition has been detected (4 – 20 mA).

To prevent improper fault indications, unused inputs should have the + (plus) and – (minus) inputs tied together and be configured for a bipolar input range. Unwired inputs can cause invalid readings. When configured for voltage inputs (no jumper is installed between Input (+) and ISENSE terminals), a broken field wire can cause readings to be non-zero and unpredictable. The field wiring terminal must not be removed when the module is in operation.

The following figure shows the 140-AVI-030-00 Wiring Diagram.

140-AVI-030-00 wiring diagram
140AVI03000 Wiring Diagram

For external wiring, the user should supply the current and voltage sources, and installation and calibration of the fuses are at the discretion of the user. It is recommended that shielded cables are used, and twisted shielded cables should be used in noisy environments. The shielded cables should be connected to the PLC’s ground. A shield bar should be used to connected the shielded cable to the ground. If you are field wiring the 140AVI03000, the maximum wire size is 1-14 AWG or 2-16 AWG and the minimum wire size is 20 AWG.

MRO Electric and Supply Company carries new and refurbished Modicon 140-AVI-030-00‘s. For more product information or to request a quote on a part, please call 800-691-8511 or email sales@mroelectric.com.
Modicon 140AVI03000
Modicon 140AVI03000
140CPU65150

Modicon Quantum 140CPU65150 – Product Spotlight

The 140CPU65150 is a Unity processor in Schneider Electric’s Modicon Quantum series. It is one of the newer models in the series of processor modules. It joins together the standard functions of the PLC and the diagnostic possibilities of a web server. It communicates using an RJ-45 connection. The module is in a double-width standard Quantum housing which requires two sequential slots in a Quantum rack. Because its web server functions are diagnostic only, software must be used to configure its services.

It has a clock frequency of 166 Mhz and has two local racks. It has 63 distributed I/O stations, 1 rack, and 3 distributed networks. It has 8000 discrete inputs and outputs of discrete in a distributed network, and 31744 discrete inputs and inputs in a remote system.  As far as application specific I/O, it can be used for time stamping, as a counter, for high-speed interrupt inputs, and as a serial link.

There are 6 optional modules that can be used with the 140CPU65150. These include, Ethernet, Modbus, Modbus Plus, Profibus DP, and Sy/Max. In a local AS interface, the module has an unlimited maximum number of connections. It also has 4 integrated connection types – Ethernet TCP/IP, Modbus, Modbus Plus, and USB. It has an expandable 8 MB of file storage, 7168 kB or expandable programming, and 768 kB of RAM. The 140CPU65150 uses a key switch memory port for on/off functionality.

The 140CPU65150 has a data rate of 10/100 Mbps. For a medium, a user should used a shielded twisted pair cable. The module has a number of services, including standard web service, Modbus TCP messaging, I/O scanning services, global data, FDR client, SNMP management, and SMTP services (email). It is compatible only with the Unity Pro software.

MRO Electric and Supply carries the 140CPU65150. For more product information or to request a replacement module, email sales@mroelectric.com or call 800-691-8511.

140CPU65150
140CPU65150

Modicon 140CRA31200 RIO Drop E/IP Adapter – Product Spotlight

The 140CRA31200 is a Ethernet RIO drop adapter in the Modicon Quantum series. It has 3 ports and uses the Ethernet IP/Modbus TCP communication port protocol. It can handle two integrated connection types: the Ethernet IP/Modbus TCP through the service port or through the device network. It is compatible with the 140CRP31200.

The 140CRA31200 has a number of local signalling channels. 1 green LED for RUN, 1 green/red LED for module status, 1 green/red LED for network communication status, and 1 red LED for I/O. This adapter module consumes one slot in the main (first) rack of the in Quantum remote drops. The extended (second) rack in a Quantum remote I/O drop does not require an adapter.

To set the location of the Ethernet remote I/O drop on the network, use the rotary switches on the front of the 140CRA31200 before you apply power to the module and before you download the application. The values that are set are applied during a power cycle. If the switch settings are change after the module has powered up, the Mod Status LED is activated and a mismatch message is logged in the module’s diagnostic system.

Because new values on the rotary switches are implemented on at the next power cycle, it is recommended that you set the values before starting the module. Valid values are from 00 to 159. These rotary switches can be manipulated on the 140CRA31200 with a small flat tipped screwdriver, and no software is required to configure or enable the rotary switches. Do not use the Stored and Clear IP settings on the Ones rotary switch, and keep in mind that the functionality of these settings do not apply to remote I/O installations.

MRO Electric and Supply carries new and refurbished Modicon 140CRA31200s. For more product information or to request  quote, email sales@mroelectric.com or call 800-691-8511.

140cra31200
140cra31200

Modicon 140CPS11420 – Product Spotlight

The Schneider Electric / Modicon 140CPS11420 is a Power Supply Module in the Quantum automation platform. It can use a summable or standalone power supply type. The module has an internal output overvoltage and overload protection. It comes in a standard module format and weights 0.65 kg. When in a standalone configuration, the 140CPS11420 uses a maximum current of 11 amps. In a summable configuration, the module has a maximum current of 20 amps. Its internal power dissipation is less than 12 watts at a full load.

A normally closed relay contact rated at 220 volts AC, 6 amp / 30 volts DC, 5A is available on terminals 1 and 2 of the power terminal strip. This contact set may be used to signal input power Off. The relay will de-energize when input power drops below 70 volts AC, when the input voltage is set to 115 volts AC, or 140 volts AC when the input is set to 230 volts AC. Its output to the Bus is 5.1 volts DC. No minimum current is required. The module’s input frequency can range from 47 – 63 Hz. the 140CPS11420’s input voltage total harmonic distortion is less than 10% of the fundamental root mean square value. The input power interruption is no less than 1 second when in a 1/2 cycle at full load, and at the minimum rated line voltage and frequency.

Remove the power line prior to insertion or removal of the module.Use only compatible combinations of summable and standalone power supplies in the Quantum back plane as stated above. If these precautions are not taken, serious injury and/or equipment damage could occur.

MRO Electric and Supply Company stocks new and refurbished 140CPS11420 modules.  For more information or to request a quote, call 800-691-8511 or email sales@mroelectric.com.

140CPS11420
140CPS11420
HMI-STU-855

Modicon Magelis HMI-STU-855 (HMISTU855) Product Spotlight

The Schneider Electric / Modion HMI-STU-855 is a 5.7 inch touch panel screen with a Magelis operating system and CPU ARM9 processor. It uses a QVGA TFT color touchscreen with a pixel resolution of 320 x 240 pixels. It uses an external supply source of 24 volts and consumes 6.8 watts of power. It has 16 MB of application battery with 64 kB available to back up data. The HMISTU855 is able to download a number of protocols including Modbus, Modbus TCP/IP, Uni-TE, and 3rd party protocols.  When using the HMISTU855, all connections to the communication ports on the bottom and sides of the unit must not put large amounts of stress on the ports. Be sure to securely attach communication cables to the panel or cabinet. Use only RJ45 cables with a functioning locking tab.

Critical detected alarm indicators and systematic function require independent and redundant protection hardware or mechanical interlocks. It is important that when power is cycled, the user waits at least 10 seconds before restoring power. Switching the power on and off quickly can damage the unit. The interface is connected to remote equipment using a RS232C or RS-485 cable. The connector that is used is a RJ45-8 pin type. The using a long PLC cable to connect the unit, a difference of electric potential can be observed between the cable and the ground, even when connected to a ground. The serial port on the HMI-STU-855 is not isolated. The signal ground and frame ground terminals are connected inside the unit. When setting up the RS-485 communication, the cable diagram for some equipment may need polarization on the terminal side. This terminal does not need any special setting because it can handle polarization automatically.

MRO Electric and Supply Company stocks many Modicon Magelis HMIs and panels, including the HMI-STU-855. For for information or to request a quote, please email sales@mroelectric.com or call 800-691-8511.

HMI-STU-855
HMI-STU-855

TSX PLCs – Compact, Flexible, Cost-Effective

TSX PLCs
TSX Nano PLCs are easy to set up and have numerous built in functions, such as memory for storing programs, battery-backed RAM, and real-time clocks for modules with 16 and 24 I/O’s. They can be installed easily on a mounting rail or base plate in the vertical or horizontal position. TSX PLCs are programmed in lists of instructions using the FTX 117 programming terminal, in Ladder or Instruction list language using software on an FT 2000, FTX 517 terminal or PC compatible. They can be used to augment extendable TSX PLCs using a single extension per base. Depending on the model they have

16 I/O : 9 inputs + 7 outputs
24 I/O : 14 inputs +10 outputs.

The following types of inputs and outputs are used:

Inputs : 24 Volts
Outputs : Relay outputs for models with ~ 100… 240 Volt power supply, transistor outputs with positive logic for models with 24 Volt power supply.

I/O Extension

Each TSX Nano base PLC can be extended using an I/O extension. This extension is created by one of the PLCs with 10, 16, or 24 i/o. The function of each PLC is defined by the position of the coding selector switch:
Position 0 : base PLC
Position 1 : I/O extension

Peer PLCs

Up to 3 peer TSX PLCs, communicating via common words, can be connected to the base PLC. In this case, only the base PLC can receieve an I/O extension. The function of each PLC is defined by the position of the coding selector switch. I/O addressing of peer PLCs is identical to that of the base TSX PLC. The extension link cable between the base PLC and PLC extensions is shielded, twisted pair  and is no more than 200 meters long.  Each PLC has 2 reserved (IW) and 2 reserved (QW) words for exchanging data between PLCs. These exchange words are updated automatically. For each PLC, the user program is only able to write to the 2 %QW output words and read the 2 %IW input words.

MRO has many Modicon PLCs available. For more information, please email sales@mroelectric.com or call 1-800-691-8511.

Modicon TSX PLCs
Modicon TSX PLCs