In industrial automation, some target products are stationary during the product inspection task, while others may be moving during this period. Even for stationary targets, the product is in a dwell for some limited period of time, before it is moves onward for the next target to move into the inspection area. If the rejection criteria for some task is simply, for example, a physically higher product as in a high-cap inspection, or a box that is dimensionally too tall, then the Inspection sensor merely needs to be looking at that height that is above the acceptable target, and if the Inspection sensor senses that detail at any time during the machines operation, the sensor will active a reject response. The sensor output can be accepted whether a product is present or not. Unfortunately, the majority of inspection task are not that simplistic.
The majority of inspection tasks in industrial automation are more challenging, requiring not only looking for one or more details on a product, with the product being either stationary or in constant movement during the inspection area. The challenge is when the absence of some feature is a reject condition for which the conveyor or machine should be stopped. In this case, which is very common, when there is no product present, obviously there also is no feature, and the conveyor or machine would never be allowed to run. This situation requires the inspection system to “know when to look”, or simply when is the product in full view of the Inspection sensor, and only accepts it output decision based on that instantaneous view. The rest of the time the product is either not present, or not fully in view, the output from the Inspection sensor is ignored. The “look now” or “windowed” inspection uses a second input Interrogate signal to know when is the product physically fully in view of the Inspection sensor.
Circa 1990-1991, Tri-Tronics modified their existing PM-8200 Control module, that had been used to coordinate this inspection task prior to this date, and introduced the refined, Product Inspection Control module PIC-1 to more thoroughly address the needs of this industrial automation inspection task. The features on the PIC-1 are extremely flexible via DIP switches, and provide what it needed for virtually any inspection task.
The Tri-Tronics PIC-1 accepts an Interrogate signal input, and one or more inputs from Inspection sensors (in sync). The PIC-1 provides two [2] separate outputs, both a triac for switching AC loads, and a NPN/Sinking open-collector output for DC signal loads.
The Tri-Tronics PIC-1 can either instantaneously provide an output for an accept or reject decision, or it can provide a selectable time delayed output (adjustable from 0-6.5 seconds) to allow the inspected product to clear the inspection area, before product rejection is made.
The Tri-Tronics PIC-1 can either latch its output until an external reset signal is provided, or one-shot its output. The latching is ideal for sounding an alarm, stopping the machine or conveyor until the operator or maintenance personnel intervene. The one-shot output, adjustable from 0-1.5 seconds, is well suited for sounding a momentary alarm or rejecting the defective product, while allowing the conveyor or machine to continue to run.
Using its DIP switches, the Tri-Tronics PIC-1 can invert its output state, invert its Inspection input, and by-pass all of it delays so that an instantaneous output follows the inspection decision.
The Tri-Tronics PIC-1 has a response time of 100 microseconds, so extremely short or fast events can be sensed and the inspection processed. With its [4] LED indicators, it confirms Interrogate input (NPN/Sinking), Inspection input (NPN/Sinking), reset input (NPN/Sinking), and output state (common to both the triac and NPN/Sinking open-collector). It has a 12-pin plug in socket, for ease of replacement at end of life.
With this capability, and the high degree of flexibility, the Tri-Tronics PIC-1 Product Inspection Control module has been very popular since its introduction.
Excel Automation/Eagle Sensors & Controls are Authorized Distributors of Tri-Tronics (1989 & 1978, respectively). Contact us for technical, application, or sales support.