HMI Touch Screen Panel for Roll Forming Lines | PLC Recipes & Alarms | ZTRFM Wiki

1. Definition

The human-machine interface (HMI) on a roll forming line is the touchscreen panel through which operators start and stop production, select product recipes, enter cut lengths and line speeds, acknowledge alarms, and view piece counters. The HMI does not execute safety logic or motion cam profiles; it reads and writes data tags in the PLC (and sometimes directly in drives where permitted) over serial or Ethernet protocols.

Industrial HMIs for roll forming are typically sealed IP65 front panels with resistive or capacitive touch, 7–15 in. displays, and 24 VDC supply. Software projects mirror machine states with color-coded indicators (Running, Stopped, Fault, Setup) so floor staff can assess status from a distance without reading small text.

2. Relation to PLC Control

The PLC remains the line controller: encoder counting, cut triggers, punch windows, VFD commands, and safety interlocks run in PLC firmware. The HMI is a supervised client. When an operator loads a recipe, the HMI writes setpoints to PLC memory words; the PLC validates ranges, applies ramp limits, and only then enables automatic run.

This separation matters for reliability. If the HMI cable is unplugged, the line should stop safely or continue finishing the current cycle per risk assessment, but it must not run unattended without permissives. Commissioning pairs HMI tag lists with PLC variable tables so integrators trace each displayed value to one DB address or Modbus register.

3. Standard Screen Layout

Machine Matcher’s roll forming HMI design pattern recommends a simple main screen plus dedicated pages for alarms, recipes, production data, and maintenance. Navigation depth should not exceed three taps for daily tasks (start, select product, clear fault).

3.1 Main Screen Elements

• Machine state banner (Running / Stopped / Fault / Setup).
• Start, stop, and jog controls with confirmation on stop during auto run if required.
• Active product name and key setpoints (length, speed, target quantity).
• Live counters: pieces completed, scrap, current line speed.
• Active alarm summary with link to alarm history page.

3.2 Touch Ergonomics

Operators often wear gloves. Buttons should exceed minimum touch target sizes (commonly 40×40 mm or larger on industrial panels), with spacing to prevent double presses. Visual feedback (color invert or beep) confirms registration. Backlight brightness should remain readable under factory lighting without glare on polyester overlay films.

4. Recipe, Length, Speed, and Alarms

4.1 Recipe Structure

A roll forming recipe bundles parameters for one profile type: cut length (mm), line speed (m/min), material thickness reference, punch pattern ID, pre-punch offset, flying shear mode, and target batch quantity. Loading a recipe writes these fields to PLC tags and may trigger a profile-change interlock (stop line, confirm tooling matches recipe ID).

4.2 Length and Speed Setpoints

Length is displayed and edited in engineering units (mm or inches per project locale). The PLC stores pulses-per-meter internally; HMI conversion uses scaled integer tags to avoid floating-point drift on small PLCs. Speed setpoint maps to VFD frequency or fieldbus speed word with min/max clamps enforced in PLC before the HMI shows “accepted.”

4.3 Alarm Management

Alarms are PLC-generated bits with associated HMI text strings. Best practice: numeric fault code in PLC, descriptive text in HMI library (supports multilingual plants). Alarm history stores timestamp, code, and state (active / cleared). Operators acknowledge alarms to reset horn; underlying fault must clear before restart permissive returns.

5. Batch Lists and Production Counters

Batch production runs a ordered list: Product A × 500 pieces, Product B × 300 pieces, etc. The HMI batch screen shows queue position, remaining quantity, and completed count. When one batch finishes, the PLC signals batch complete; the HMI loads the next recipe row or prompts operator confirmation depending on automation level.

5.1 Counter Types

• Shift total — Resets per operator shift handover.
• Job total — Resets when new batch list activated.
• Lifetime / maintenance — Total cuts for shear blade wear tracking.
• Scrap counter — Increment on manual scrap button or length fault.

6. Modbus, Ethernet, and PLC Tag Mapping

6.1 Common Protocols

Roll forming HMIs connect to PLCs via:

• Modbus RTU on RS-485 — Common on Delta DVP PLC + DOP HMI pairs; single cable, moderate speed.
• Modbus TCP / Ethernet — Same register map over TCP; preferred for longer cable runs.
• PROFINET / S7 protocol — Siemens KTP panels to S7-1200/1500 on plant Ethernet.
• EtherNet/IP — Some North American OEM lines with Allen-Bradley PLCs.

6.2 Tag Mapping Discipline

Integrators publish a register map: HMI address 40001 = cut length high word, etc. Delta DOP projects use Delta’s DIAScreen or legacy software to bind numeric displays and buttons to Modbus addresses. Siemens KTP Basic panels use WinCC in TIA Portal; HMI tags link to PLC DB symbols with consistent naming (e.g., DB_Recipe.CutLength_mm).

Separate HMI traffic from VFD motion fieldbus where possible using managed switch VLANs to reduce broadcast load on critical drives during high-speed production.

7. Operator Workflow

A typical shift workflow on a multi-product roll forming line:

1. Power on; HMI shows Stopped; PLC completes self-test (hydraulic pressure, guard doors, drive ready).
2. Operator logs in at Operator level; selects recipe from product list; confirms load (writes setpoints).
3. Thread strip at jog speed from Setup screen; verify encoder count increments.
4. Return to Main; press Start; PLC ramps VFD to recipe speed; production counters reset if new batch.
5. Monitor live speed and count; on alarm, line stops; operator reads fault text, fixes cause (e.g., coil end splice), acknowledges, restarts.
6. At batch complete, HMI prompts next product or auto-loads per queue; supervisor may edit recipes at Supervisor login only.

Machine Matcher emphasizes restricting recipe edit rights to supervisors or engineers so floor operators cannot accidentally change punch offsets or length limits that affect structural compliance.

8. Maintenance and Diagnostic Screens

Maintenance pages are password-protected. They expose signals operators should not toggle during normal run:

• Digital input matrix (limit switches, sensors) with live on/off indication.
• Encoder raw count and calculated meters since reset.
• VFD and servo fault codes with link to manufacturer code list.
• Manual override for hydraulic valve test (guard door closed interlock still active).
• Hours run counters for decoiler brake lining or shear blade replacement interval.

Document HMI backup procedure: Delta projects saved as compile files on PC; Siemens KTP Basic requires original TIA project for edits (upload from device is not supported on Basic panels per Siemens forum guidance). Store gold-copy projects off-panel to avoid loss when hardware is replaced.

9. Hardware Examples (Delta DOP, Siemens KTP)

Two widely deployed HMI families on roll forming equipment illustrate feature tiers available to machine builders.

9.1 Delta DOP Series

Delta DOP-100 and DOP-300 touch panels pair with Delta DVP PLCs and ASDA servos in packaged lines. DOP-100 Basic/Standard/Advanced tiers offer 7–15 in. displays; programming via DIAScreen. Delta packaging solution literature shows DOP-B HMI in flying shear cells alongside DVP-SE PLC and A2 servo E-CAM. Communication options include Modbus and Ethernet variants depending on model suffix.

9.2 Siemens KTP Basic

Siemens SIMATIC HMI KTP700 Basic PN (7 in.) appears in flying shear roll forming forum examples with S7-1511T PLC. KTP Basic connects to S7 on Ethernet using integrated protocol; it does not support PROFINET IO device mode or Direct Keys on Basic panels. Integrated HMI in FlyingSawBasic example supports simulation without physical drives for commissioning.

Comfort-panel upgrades (e.g., TP700 Comfort) add larger memory and IO-device options when project budget allows; Basic panels remain sufficient for length/speed/alarm/counter functions on standard roll forming lines.

Related topics

• PLC Control Systems in Roll Forming
• Hydraulic vs Servo Cutting Systems