- What This Cheat Sheet Covers (and What It Doesn't)
- C-309 at a Glance: Verified Facts
- Domain 1: Analog Instruction Programming
- Domain 2: Troubleshooting Analog I/O
- Domain 3: Program Control Instructions
- Domain 4: Subroutine Instructions
- Domain 5: HMI Objects Interacting with a PLC
- Domain 6: Information, Diagnostic and Alarm Messages
- Silver vs. Gold: Delivery Mechanics
- What Is Still Unverified
- A Domain-Ordered Review Sequence
- Frequently Asked Questions
- C-309 is Programmable Controller Systems 2, issued through the Smart Automation Certification Alliance (SACA).
- Six preparation objectives cover analog logic, analog troubleshooting, program control, subroutines, HMI objects, and HMI messages.
- Silver is a proctored online written exam; Gold adds an observed hands-on assessment on SACA-approved equipment.
- Question count, time limit, retail fee, and pass mark were not verified, so confirm them with your center.
What This Cheat Sheet Covers (and What It Doesn't)
This page is a one-page-style review of Programmable Controller Systems 2 (C-309), the second-level programmable controller credential in the Smart Automation Certification Alliance (SACA) family. It is built around the six preparation-curriculum objectives that appear in provider course documents for C-309-coded standards. If you need the full picture of how those objectives are organized, the C-309 Exam Domains guide covering all 6 content areas goes deeper on each one.
Because the objectives are unweighted in the sources we reviewed, this sheet does not tell you to spend a certain percentage of time on any domain. Instead, it tells you what each domain asks you to do, what a hands-on version of that skill looks like, and where candidates commonly need to slow down and think.
C-309 at a Glance: Verified Facts
| Item | What We Can Say |
|---|---|
| Credential name | Programmable Controller Systems 2 (C-309) |
| Certifying body | Smart Automation Certification Alliance (SACA) |
| Silver delivery | Proctored online written exam through the SACA portal at participating centers |
| Gold requirement | Silver plus an observed hands-on assessment using SACA-approved equipment |
| Preparation objectives | Six (309.01 to 309.06), covering analog, program control, subroutines, and HMI |
| Written question count | Not verified |
| Written time limit | Not verified |
| Individual retail exam fee | Not verified |
| Universal pass mark, retake, renewal rules | Not verified |
Two practical notes. First, SACA education and industry membership benefits can provide certification access for eligible enrolled students and member-company employees, and that access is distinct from tuition, equipment, or local center charges. Second, do not assume a college course sequence is an admission rule. Course prerequisites at a given school, including the C-207/C-208 sequence shown in one degree-pathway example, are not verified issuer-wide requirements. For the eligibility question in detail, see C-309 Requirements: Eligibility, Prerequisites and How to Qualify.
Domain 1: Analog Instruction Programming
Program and operate a PLC logic program that uses analog instructions
This is the foundation of the credential. You are expected to write logic that reads, scales, compares, and acts on continuous values rather than simple on/off bits.
- Understand how an analog input module converts a field signal into a raw integer count in a data table or tag.
- Scale raw counts into engineering units (for example, counts into degrees, pressure, or level) using the move, math, or scale/scale-with-parameters style instructions your platform provides.
- Use compare instructions (greater than, less than, limit test) to turn an analog value into discrete decisions such as high-level or low-level conditions.
- Write scaled values back out to an analog output to drive a valve, drive speed reference, or similar device.
Concepts to have cold
- Raw vs. engineering units: the PLC only sees counts. Everything meaningful to a human is a calculation you wrote.
- Linear scaling: know the slope-and-offset relationship between input range and output range, and be able to compute a midpoint by hand to sanity-check your logic.
- Data types: integer vs. floating-point choices affect resolution and rounding in scaled results.
- Operate, not just program: the objective says program and operate. Expect to run the logic, watch values change, and confirm the process responds correctly.
Domain 2: Troubleshooting Analog I/O
Troubleshoot a PLC program application that uses analog I/O
Domain 2 flips the perspective. Instead of building a working analog application, you diagnose one that is not behaving correctly.
- Separate field problems (sensor, wiring, power, loop signal) from program problems (scaling, wrong address, wrong data type).
- Use online monitoring to compare the raw count against the expected count for a known input condition.
- Recognize the signature of common faults: a value stuck at the bottom or top of range, a value that moves but never reaches the expected span, or a value that jumps erratically.
- Check module configuration, channel assignment, and range settings before rewriting logic.
Domain 3: Program Control Instructions
Program and operate a PLC logic program that uses program control instructions
Program control instructions change how and whether the processor executes portions of the program. They are powerful and easy to misuse.
- Understand the idea of conditionally skipping or jumping over rungs and what happens to the state of outputs in skipped code.
- Know how master-control-style instructions can disable a zone of logic and what that does to outputs inside the zone.
- Be able to explain why bypassing logic can leave outputs latched or frozen in their last state, depending on instruction type.
- Use these instructions deliberately, with clear labeling, rather than as a shortcut.
The exact instruction names vary by controller family, so anchor your preparation to the concept and then confirm the mnemonics on the platform your center uses. The exam-style trap here is usually state: candidates know the instruction exists but forget what the outputs do while the logic is not being scanned.
Domain 4: Subroutine Instructions
Program and operate a PLC logic program that uses subroutine instructions
Subroutines organize a program into callable blocks so logic can be reused and a large program stays readable.
- Understand the relationship between a main routine and the subroutines it calls, including how execution returns to the calling point.
- Know how to create, call, and return from a subroutine on your platform.
- Understand how parameters or shared data are passed in and out, and the difference between shared tags and passed values.
- Recognize that an uncalled subroutine never runs, which is a classic cause of "my logic does nothing" troubleshooting.
Domains 3 and 4 work well together. Program control decides whether code runs; subroutines decide how code is packaged. A well-structured exercise calls a subroutine only when a condition is met, which exercises both skills at once.
Domain 5: HMI Objects Interacting with a PLC
Program and operate an HMI project that uses objects to interact with a PLC
The credential extends beyond ladder logic into the operator interface. Here you build screens whose objects read from and write to PLC data.
- Create HMI objects such as push buttons, indicator lights, numeric displays, and bar graphs or similar visual elements.
- Bind each object to the correct PLC tag or address so that a button press sets a bit and a lamp reflects an output.
- Understand the direction of data: an indicator reads, a pushbutton writes, and a numeric entry may do both.
- Verify communication between the HMI and the controller before blaming the screen design.
A useful mental test: for every object on a screen, you should be able to say which tag it touches and whether it is reading, writing, or both. Mismatched tag names and data types are the most frequent reason an otherwise correct screen appears dead.
Domain 6: Information, Diagnostic and Alarm Messages
Program and operate an HMI project that uses information, diagnostic and alarm messages
The final domain is about communicating machine state to the operator through text messages that appear when conditions occur.
- Distinguish the purpose of each message type: information messages describe normal conditions, diagnostic messages help locate the cause of a problem, and alarm messages demand attention to an abnormal condition.
- Trigger messages from PLC bits or values so that a message appears when its condition is true.
- Write message text that is specific enough to act on, rather than vague.
- Understand acknowledgment and display behavior as it applies to your HMI platform.
Key Takeaway
Domain 2 and Domain 6 are a natural pair. The analog fault you learn to diagnose at the controller can become an alarm or diagnostic message at the HMI, such as a low-level alarm driven by a scaled analog value. Practicing that full chain, from sensor to scaling to compare to alarm message, rehearses four of the six domains in one exercise.
Silver vs. Gold: Delivery Mechanics
C-309 is delivered through SACA's tiered model. The written component is the Silver level: a proctored online written exam taken through the SACA portal at participating centers. Gold requires that Silver result plus an observed hands-on assessment using SACA-approved equipment.
| Level | Format | What It Tests |
|---|---|---|
| Silver | Proctored online written exam via SACA portal | Knowledge of the six objective areas |
| Gold | Silver plus observed hands-on assessment on SACA-approved equipment | Ability to perform programming, troubleshooting, and HMI tasks on real equipment |
Because Gold is hands-on, bench time matters. Reading about analog scaling is not the same as watching a trainer's analog input change as you turn a potentiometer or adjust a simulated signal. If you are aiming for Gold, prioritize equipment access early. Details on how costs and center charges fit together are in the C-309 certification cost breakdown, and scheduling questions are covered in C-309 Exam Dates: Testing Windows, Deadlines and Scheduling.
What Is Still Unverified
Honest preparation means knowing what you cannot yet rely on. The following were not verified in the research behind this sheet, so confirm them directly before you plan around them:
- The exact number of written questions.
- The written exam time limit. Course hours and hands-on assessment time are not a written-exam timer.
- The individual retail exam fee.
- A universal pass mark, plus retake and renewal rules. See C-309 Passing Score: Exactly What You Need to Pass for how we track this.
Also note that the college course documents reproduce credential-coded preparation standards, but they do not establish the latest issuer exam version. Always compare against your testing center's current materials. If you want a broader orientation first, What Is C-309? is a good starting point, and How Hard Is the C-309 Exam? discusses difficulty in context.
A Domain-Ordered Review Sequence
If you only take one scheduling idea from this page, make it this: review in dependency order, not numerical order for its own sake. Analog logic feeds troubleshooting, program control and subroutines feed program structure, and the HMI domains sit on top of all of it.
Analog Foundations (Domain 1)
- Hand-calculate scaling for at least three different input and output ranges.
- Build and run a scaled analog input with compare-based high and low conditions.
Analog Faults (Domain 2)
- Introduce deliberate faults: wrong range, wrong address, disconnected signal.
- Practice the process-to-field-to-wiring-to-module-to-tag-to-math diagnostic order.
Program Control and Subroutines (Domains 3 and 4)
- Write a main routine that conditionally calls a subroutine.
- Observe and document output behavior in bypassed or disabled logic zones.
HMI Objects and Messages (Domains 5 and 6)
- Bind every screen object to a tag and confirm its read or write direction.
- Drive an alarm and a diagnostic message from the scaled analog value you built in Week 1.
Four weeks is an illustration, not an issuer recommendation; stretch or compress it to match your lab access. For a broader plan, the C-309 Study Guide on passing on your first attempt lays out additional preparation options, and you can check your readiness with questions on the C-309 practice test site.
Last-pass checklist
- Can you scale a raw analog count to engineering units without looking anything up?
- Can you name the first three things you check on an analog input that reads zero?
- Can you say what happens to outputs inside a bypassed or disabled logic zone?
- Can you explain how a subroutine is called and how execution returns?
- Can you trace any HMI object to its tag and state its data direction?
- Can you distinguish information, diagnostic, and alarm messages by purpose?
If any answer is a hesitation, that is your next lab session. Extra practice questions and domain drills are available at our main practice platform, and if you are weighing whether the effort pays off, see Is the C-309 Certification Worth It? and C-309 Jobs for context on where the skills get used.
Frequently Asked Questions
C-309 here means Programmable Controller Systems 2 from the Smart Automation Certification Alliance. This sheet covers six preparation objectives: analog programming, analog troubleshooting, program control instructions, subroutine instructions, HMI objects, and HMI information, diagnostic and alarm messages.
No weighting was verified. The six items are preparation-curriculum objectives drawn from provider course documents, not confirmed official weighted exam domains, so plan to be competent in all of them rather than favoring one.
The Silver level is a proctored online written exam taken through the SACA portal at participating centers. Gold requires Silver plus an observed hands-on assessment using SACA-approved equipment.
The exact question count and time limit were not verified. Course hours and hands-on assessment time are not a written-exam timer, so confirm both with your participating center before you test.
Not as a verified issuer-wide rule. College prerequisites and sequences such as C-207/C-208 appear in specific program examples, but they are not confirmed admission requirements, so check with your center or program.