PLC Troubleshooting Dialog Boxes
SC Johnson Wax Professional needed a new processing facility at the Waxdale campus in Racine, Wis., to produce and package a full range of cleaner and floor stripper products with a Just-In-Time (JIT) production model. Small and medium batches were needed on five production lines with a quick cycle time to meet incoming orders.
SC Johnson Wax Professional needed a new processing facility at the Waxdale campus in Racine, Wis., to produce and package a full range of cleaner and floor stripper products with a Just-In-Time (JIT) production model. Small and medium batches were needed on five production lines with a quick cycle time to meet incoming orders. This would reduce tank and warehousing requirements and allow fast reaction to orders over a constantly expanding set of products.
SC Johnson Wax solicited help of Stone Technologies (St. Louis, Mo.) to meet manufacturing goals. Project goals included reduced wastewater discharge; standardized batches in process; accounting for variances in raw material assay or potency; conformance with GMP and FDA Validation Standards for Registered Products; increased product consistency; enhanced reporting for batch production; and producing small- to medium-sized batches with a quick cycle time.
Stone Technologies provided the integrated solution using the following technologies: Wonderware InBatch and InTouch software; Windows NT server, workstation, and remote access server (RAS); Allen-Bradley 5/80E PLCs with 1771 and flex I/O; Compaq 1500 servers with RAID 5 array, redundant and hot swappable drives and power supplies; Ethernet communications 10 MB 10base T and 100 MB fiber; remote I/O connection of the VFD and Rice Lakes scales; and DH+ communications for peer-to-peer PLC communications and small operator interfaces.
These technologies provided the necessary control to meet manufacturing goals but presented an additional challenge of how to troubleshoot the system when a problem occurred. Stone Technologies devised a method to troubleshoot the vast majority of device failures and other control system difficulties without PLC programming software.
The PLC code, descriptors, InTouch tags, InBatch tags, and validation documentation were developed in a project database and exported into the components. The database used object relationships to cross reference interlocking between batch phases and their associated devices. Data access was through InTouch's ODBC (open database connectivity) interface to drive a series of troubleshooting and testing screens, which allowed phase interlocks and faults to be easily analyzed.
With "InBatch," the Phase Logic is a sequence of control operations executed within the PLC control system under supervisory control of the batch execution engine and operator via the SCADA system. The initial state of the phase is always "Ready" or "Interlocked." In "Ready" mode, the phase can accept a "Start" command and begin execution of its steps.
With the system in either "Interlocked" or "Held," the operator can use the built-in troubleshooting dialog screen, accessible via the HMI screens, to view status of the PLC phase interlocks. This provides information for the operator to quickly identify problems or system conditions.
Stone Technologies met all goals for batch cycle times, product flexibility, and product consistency. The processing system consistently stays ahead of packaging demand even with pre-emptive scheduling requests. SC Johnson Wax has no dedicated support personnel maintaining the batch system.
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