Sepasoft Settings and Changeover: machine recipes on Ignition, setpoints, inheritance, variances and change logs

On a line with several machines, a product changeover means setting speeds, temperatures, weights and formats on each machine, often from the panel of each machine, and every manual entry is a chance for an error. Sepasoft's Settings and Changeover module for Ignition keeps machine setpoint recipes in one place, writes them to the machines when a recipe is selected, and logs any value that later drifts from the recipe. This article explains how the module works, from Sepasoft's MES Module Suite user manual: what Sepasoft means by a machine recipe, how setpoints are configured and inherited, how recipes are selected and checked, and how variances, security and changes are recorded. Which Sepasoft module fits which plant need: Sepasoft MES modules.

1. A machine recipe, not a batch recipe

Sepasoft defines a machine recipe as the set of machine settings that equipment on a line uses to process material consistently for a given product. A process engineer qualifies these settings as the Process Of Record for that product on that line, and the module's purpose is to download them from the MES instead of having operators enter them. Sepasoft separates this from a batch recipe: a batch system also handles equipment definitions, sequencing, inventory checks and alarms, which is the job of its Batch Procedure module. Batch control on Ignition is covered in Sepasoft Batch Procedure.

2. From recipe to PLC

When a recipe is selected, its values are written to Ignition tags. If those tags are OPC tags mapped to PLC memory, the values reach the machine; a value can also go to a memory tag, for example a barcode number shown for operator verification. Setpoints can be strings, integers, floats and other types, and can be managed for a whole line or for individual machines. Sepasoft notes that write permission must be enabled in Ignition when the module writes to tags in a remote tag provider.

3. Configuring setpoints

Setpoints are configured in the Equipment Manager, under Settings & Changeover, from MES version 3.81.9 RC 3. The main settings for each setpoint are:

4. Inheritance and sub-recipes

Production items below the area level can take their values from the parent item or from their own defaults, set by the Inherit Recipe Values mode: Parent Recipe or Equipment Default. Only setpoints with an Ignition tag assigned appear in the recipe editor, so a value inherited from the line but irrelevant to a machine simply has no tag on that machine. A sub-recipe mask lets a few digits of the product code choose the recipe for one machine: an X ignores that digit and an asterisk uses it. Sepasoft's example is a tape machine whose settings depend only on case size, coded in one digit of the product code, while the other machines keep their normal recipes.

5. Selecting and checking recipes

Selecting a recipe for a line also selects it for all child cells, cell groups and locations, unless the EnableRecipe tag of a child is set to false. In Perspective, the Recipe Selector List shows the recipes of one production item and marks the running one as Active; recipes can also be selected with a combo box or by script. With OEE Downtime or Track & Trace installed, the recipe named in the operations segment is downloaded when the segment begins. The module creates production tags that show the state of each item, among them:

6. Variances, security and change records

After a recipe is selected, each monitored tag is compared with a low and a high threshold, set as a percentage of the recipe value, a fixed offset or fixed values; a change outside the band is logged, and without thresholds every change is logged. Sepasoft's example is a fill weight of 50.2 with thresholds that give a band of 47.69 to 55.22, so 51.0 is accepted and 46.0 is logged. Recipe value security uses Ignition roles to limit who may change which values and by how much, and can be inherited down the equipment tree. Every change to a recipe, from the editor, an import or a script, is recorded with who, when, the previous value and, optionally, a required note; Sepasoft points out that direct changes to the database are not detected, so the database itself needs to be secured.

What we settle before configuring recipes

These are TDL's working habits, not Sepasoft requirements:

• Which setpoints each machine really needs from the MES, and which stay on the machine panel.
• The PLC tags for each setpoint, their data types and whether the PLC accepts writes while running.
• The variance band for each monitored value, agreed with the process engineer.
• Who may change recipe values, and whether a note is required for each change.

How TDL approaches it

TDL Industrial Automation is a Sepasoft MES Certified Integrator and an Ignition Certified Integrator. TDL's recipe work so far has been on Rockwell Automation platforms: recipe editors and automatic size change on packing lines, and FactoryTalk Batch and PlantPAx recipe control. Where a plant chooses Settings and Changeover, TDL maps the setpoints to the line PLCs. More on this service: MES on Ignition with Sepasoft.