Five questions, spanning the whole part, plus a Riverside review. Work them without your notes. These are judgment questions: there's a right way to think about each one, not a sentence to memorize.
CHECKPOINT
L18 Control PhilosophyA sorter on a live system starts sending a share of cartons to the wrong doors. The controls contractor says the PLC is fine and the mechanical team says the divert fires on time. Using the five-layer topology, walk how you'd figure out which layer actually owns this problem, and name what you'd ask at each layer to isolate it.
L19 Sensing and IdentificationA new engineer proposes mounting the registration photoeye at a slight angle across the belt because it "catches more of the carton." A share of reads are landing in the wrong position and a share of barcodes are coming back no-read. Explain what the angle does to a registration read, what a no-read rate is, and what has to exist downstream so a no-read does not stop the line.
L20-L21 Machine Controls / Power and NetworksAn accumulation zone that feeds a sorter induction is configured signal-to-release, and its Aux I/O gets disconnected during a maintenance call. Product releases uncontrollably into the induction. Separately, the customer's IT director wants to put the safety e-stop messaging and the office email on the same flat network to save a switch. Explain what went wrong at the zone and what the safe default should have been, and make the case for how the safety and control traffic should be treated on the network.
L22 Data and DecisionsA scan point is 15 feet upstream of the first divert and the belt runs at a fixed speed. Partway through design, the customer's IT lead confirms the WMS response time is slower than the estimate everyone had been using. Explain why that number is a physical design constraint and not just a software setting, what physically has to be re-checked when it changes, and what the design levers are if the system can no longer respond in time.
L23 Recovery, Diagnostics, and the OperatorDuring a peak wave, a destination lane fills, the hospital lane backs up, and then the WMS connection drops for ninety seconds. Explain how you'd want the system to behave in each of those three moments so the whole line doesn't stop, and what you would have had to design ahead of time for each of them to work.
YOUR RIVERSIDE WORK SO FAR
Deliverable
Quality Criteria
Controls architecture summary
Every system component placed on the correct one of the five layers
EZLogic accumulation logic on Layer 1; sorter routing decision on Layer 3 WCS; WMS interface at the Layer 3/4 boundary
The three-part handshake at the sort point walked end to end
The anti-gridlock / induction-throttle point identified
The degraded-mode behavior when the WMS is down stated
Ray placed as the Layer 4/5 owner
Setpoints list
Belt speeds by section; VFD ramp rates at the decline
PLC delay values at transfer points; accumulation zone release modes
The fail-safe (signal-to-stop) default stated
Every value specified now, not deferred to commissioning
The list flagged as belonging on the installation drawing (that placement is Lesson 28)
Interface map + latency budget
Each system-to-system link named (PLC to WCS, WCS to WMS), with its payload and its failure behavior
The latency budget uses the confirmed 1-second WMS response, not the half-second placeholder
Shows the distance a carton travels in 1 second at the specified belt speed, and confirms the 24-inch transmit-point-to-divert distance is sufficient, including the 0.25s divert actuation
States what changed when the number moved from 0.5 to 1.0
The timeout behavior defined: no response in the window routes to the hospital lane