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SCADA & HMI Training : PLC Training Best Practices

SCADA Training  

This is section 10 SCADA & HMI Training of the PLC Training Best practices. Remember Industry standards are your starting point to developing best practices. Industry standards like

ANSI/ISA-99.02.01; ISA SP-100; ISA18.2; ISA101; ISO/IEC 14908.1 & 14543(KNX); ASM 2nd edition. Also for alarm standards, study EEMUA191, OSHA, HSE and NAMUR.

When you are ready to move on above and beyond Industry standards as a constant improvement program,  learn and implement industry HMI and SCADA programming best practices and security measures so your HMI and SCADA programs are more user friendly, value added and secure for your customer. That is part of what the PLC training tip and best practices contained in these 10 sections address. This page is for Section 10 of these 10


Section 10: SCADA & HMI Training:

The tips and best practices on this page will be helpful for ...

The maintenance manager, commercial electrician, industrial electrician, instrumentation tech, mechatronics tech, industrial engineer, industrial IT person industrial software programmer or the mechanic cross training and others.

Bookmark this page or site; as new best ways for PLC technician, industrial electrician, instrumentation technician and others to perform basics task are verified, they will be added here.

PLC Training Best Practices:

10.1 SCADA & HMI Training Topics:

Learn sections 1-9 (PLCs/PACs) before tackling SCADA. While SCADA is just a computer software, the 'SCADA system' (all devices SCADA software accesses) will be ever growing and changing.

Take HMI training before moving up to SCADA.

Take PLC/SCADA Basics course, get hands on experience with 2 or more brands of SCADA software. (If you do not yet have SCADA with current employer, some major brands you could start with are WinCC, FactoryTalk or Wonderware.

IT network management. The core of SCADA systems is communications, without it they are useless. So equal training should be given for setup, maintenance and management of various device communications.

Adding device drivers for communications.

Understand ST SQL quires, XML and CSV files.

Understand integrated development environment (IDE) , DDE and OPC.

Get familiarized with graphic libraries, customizable reports, and programming language.

Organizing & filtering alarms.

SPC, trend charts, recipe management, logging and historians.

Python programming language.

Visual Basics Script.

Familiarize your self with data record keeping regulations associated with your particular industry.

10.2 HMI Training

Inventory all HMIs in your facility

10.2.1 Working with HMIs

Best practice is to use same brand of HMI as the PLC the HMI is talking too, it results in less downtime and cost over the life of the equipment.
Just as you should inventory all your facilities PLCs and back up each program every 6 months and/or after change, so should inventory and back up all your HMI programs.
In addition to standard data collected while inventorying PLCs, like with the PACs, you need to make not of software and firmware revisions, also specific to HMI/SCADA systems inventory, you need to make not of computer operating system each uses. One built on a custom Unix operating system for example may not be in the normal company network back up plan, so you will need to back up manually.
With HMI, IDE, DDE and scripting are also necessary learning topics.
More coming soon...

10.2.2 Working with HMI Design

As HMI (Human Machine Interface AKA: operator station) is also the bases in which SCADA software is designed, this section applies to both stand alone HMI units and SCADA software's operator interface screens.
HMI training (and first part of SCADA training) should follow standard design pattern; application manager (HMI/SCADA development software use), then HMI/SCADA screen development (window maker/editor), then window viewer (runtime).
Learn the common and best methods to visualize production data on screen with graphic objects.(less is more, visual confirmation of buttons pressed, etc.)
Alarms should be on the top of the page. (To maximize attention of the top to bottom, left to right reader.)
Present process data in context to increase the operator’s situation awareness. (IE: don't just show pump over temp, show supply valve off to pump. etc.)
Best practice is to avoid graphics that replicate analog meters (or at least have visible digital display of analog value above analog meter), using bar or other graph results in better operator interpretation.
Use color, motion, and sound sparingly. Keep it simple.
Best practice is to not only display values, but indicate where that value is within context of acceptable range.
Colors: Keep it simple, use neutral colors like grey as default, save bright bold colors for objects that need operator's attention. Use text colors that contrast the background. (Do not use white text on a yellow background for example.) For overall HMI background, use pastel shades such as light grey, light brown etc. (black and white may cause too much screen glare.)
For critical alarms, account for possibility operator is color blind, make alarm blink too. (this better grabs their attention too.)
User Information: Keep it simple, use navigation screens, limit objects per screen, use open new screen for additional details theme.
Best practice is level 1 screen overview/main menu, level 2 screen monitor/control, level 3 screen more details/help. (no level 4 screens)
Just like documentation is critical to PLCs/PACs, so holds true for HMI. Have plenty of help screens and details screen to explain objects/data.
Organize screens by user. Operator, password protected maintenance access screens and OEM access screens.
Track operator usage like is done with websites, so you can optimize design during next update. (find out which screens are accessed most and why, adjust navigation and objects for maximum user friendliness.)
Also like website design, make sure user does not have to click more than 3 times to get to any specific information.
Spell out acronyms whenever possible.

10.3 SCADA Training

Never use default node and IP address

Develop a clear understanding of ICS cyber security.

SCADA security should be considered as important as performance and safety.

Friends don't let friends put SCADA on the Internet. There are 146,137 SCADA systems online, (at least) 15000 can be hacked by script-kiddie. (Ref by SCADA brand)

Learn about the three types of logging: cyclic driven, event driven, and a hybrid of both. Applications for alarm logging and tag logging.

10.3.1 SCADA Communication

Failure probability (physical) apply to HMI/SCADA communication troubleshooting too. 90% of established communication network failures are due to physical attributes like  connection, cable, power supply or communication card. Second most likely cause is communication drivers.

For troubleshooting networks if failure probability method above does not yield desired results, next you should use the Open Systems Interconnect Model. IE: Start with physical layer (mentioned above), then data link layer, network layer, transport layer, session layer, presentation layer, application layer.

Modbus communication for both Serial and TCP/IP can be optimized for speed by grouping same type of tags with contiguous I/O address. At least group ‘like’ data tags into arrays to reduce network communication overhead.

When sending out alert messages, make user friendly top priority, color coding preferred. alert level/category at top of message. Related root cause PLC/PAC tag/address in brackets at bottom.

Be familiar with SCADA system's watch-dog timers or “heart/life beat signals” that ensure that communications between devices are working.

If you have a choice of placing PID loop in SCADA or PLC, place in PLC as it will eliminate communication delays and reduce SCADA network bandwidth.

For BMS be familiar with ASHRAE's BACnet communication protocol  and with LonTalk.

10.3.2 SCADA Troubleshooting

After SCADA systems have been commissioned, most failures are hardware, so utilizing SCADA skills is less frequent for maintenance personnel. This means they need regular refreshers in SCADA knowledge learned.
SCADA downtime can be serious, ranging from lost data that will affect regulatory compliance to unscheduled downtime that impacts customers.
Standard Failure probability (physics) should be applied to troubleshooting SCADA too. In order of most likely to least likely; Mechanical (external to HMI/SCADA or PC they reside on), electro-mechanical (external to SCADA PC/server first, then SCADA PC/server), Communications, PC parts(High current then Low current, so higher current devices like power supplies (UPS too) and VFDs are higher probability). See also PLC Troubleshooting for lower level down to sensors.
Make tag's source/address available on hover or right click/properties users can see or gain access to without having editing software.
Every device connected to SCADA system should have an “equipment online” signal sent from the equipment to the SCADA software.
Be aware of mechanisms in SCADA software that record and re-instate default set points on the equipment.


 Back to ...  Section 1: PLC Training Prerequisites Best Practices.