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The Betatronics® TIMELOG-16 System is a very useful tool to monitor the time of events to 1/100 sec over long time periods.

 

Betatronics® TIMELOG-16
A Time Logging Peripheral:

PURPOSE:

The purpose of this device is to help you improve the efficiency of your machine, assembly line, or process. TIMELOG measures the time of one or more events in a machine or process to monitor or troubleshoot the system. An event is anything that can be converted to an electrical ON-OFF signal (binary).

Process monitoring --- TIMELOG can be used to measure machine cycle time, production rate, blocked and starved conditions, and point to bottleneck areas. Bottleneck may also be referred to as constraint. Blocked is when a machine is done, but a down stream interference prevents the done part from being released. Starved is when a machine is ready to receive a new part, but one is not available. The slowest stations on your line are the bottlenecks and these should never be starved or blocked.

Troubleshooting --- TIMELOG allows unattended measurements over long time periods to trap random intermittent problems in a machine cycle to help identify the cause. Using RS485 communication the monitoring computer can be in a protected area at a great distance form the machine under test.


SUMMARY of CHARACTERISTICS:

The maximum number of inputs per TIMELOG module is 16. The maximum number of TIMELOG modules is about 32, or 512 inputs per serial channel on the monitoring computer. Of course more than one serial channel can exist on the computer, and thus more than 512 inputs.

The time resolution is 10 milliseconds (.01 sec.). For most transitions the short term accuracy is aproximately +/-20 milliseconds. Digital filtering is used to reduce false transitions. Worst case long term accuracy is about 4 seconds per day, but all stations can be resynchronized at any time.

The transition times are stored in an internal buffer of the TIMELOG module. This allows good timing accuracy determined by the TIMELOG internal clock. If the internal buffer were not used, then the monitoring computer would have to scan all of the stations at a high rate in order achieve 10 millisecond resolution.

The TIMELOG module always operates in a half duplex COMMAND RESPONSE mode. Communication is via RS232 (single module only and short distance), RS422 (single module and longer distance), or RS485 (multidrop up to 32 modules per 2 or 4 wire bus and moderately long distance). Only one RSxxx mode is selectable for input. But both RS232 and RS4xx output simultaneously. The RSxxx line drivers are isolated from the internal circuitry. This minimizes ground loop problems between machines. Maximum cable length is 18 to 50 ft for RS232, and 1000 ft for RS422 and RS485 at 19.2 kbaud. RS232 and RS485 use a shielded twisted pair. RS422 requires 2 twisted pairs and shield. Baud rate is 19.2 kilobits per second. Length is dependent on cable capactance, loading, and baudrate.

The monitoring computer should employ an optically isolated serial card for RS422 or RS485.

A single bus system with mutiple TIMELOG modules should handle up to 24 stations with 10 transitions per machine cycle per station with an average pallet to pallet time of 12 seconds with an accuracy of approximately +/-20 milliseconds. The 240 transitions per 12 seconds is saturation for the 19.2 kbaud rate.

Two Typical APPLICATIONs:

Process monitoring --- permanent installation on a machine or line. In this application more than one TIMELOG module is connected to a production line. A single TIMELOG module might be connected to one or two stations. Bottleneck and nearly bottleneck stations need to be monitored. However, monitoring all stations will provide the greatest amount of information.

This described application is for a non-synchronous differential assembly line. However, TIMELOG is applicable to many different lines and machines.

A number of critical stations on the line are connected to the multidrop bus and to the monitoring computer. This system can be used for blocked and starved detection and thus determinition of one or more bottlenecks. Especially useful on nonsynchronous lines.

Typical signals for each station are ---
(1) On-deck pallet present and in position to be released to the station. The pallet sensor should only indicate presence when this pallet is essentially against the on-deck pallet stop. If this signal is NOT present at the time the in-station operation is done, than a starved condition exists.
(2) Pallet clamped.
(3) Good part present in-station.
(4) Part reject in this station.
(5) Down-stream is clear. There is enough space down stream for the in-station pallet to be released and not block the complete entry of the on-deck pallet into the station. This is usually a photocell beam diagonally across the line and intercepted by the pallet base. If down-stream is NOT clear, then the station is blocked. Even if no part is on the pallet we need to know if the pallet blocks the station.

At the on-deck pallet position of each station a photocell or prox switch sensor is used to detect the presence of the on-deck pallet. This is one input to the TIMELOG module.

If the pallet clamp function operates as soon as the pallet is in place in station and releases as soon as the station function is done, independent of blockage, then station cycle time can be determined from this single input. The minimum pallet-to-pallet time can be calculated by adding pallet transfer time to the station cycle time. From this the instantaneous throughput, and various averages of this station can be calculated. However, averages are better determined from a time span and the number of parts with that time.

A good part present signal is another input, as well as reject from this station. Last if the pallet position following this station has a pallet present detector, then blockage of this station can be detected.

For a well designed station these signals will inherently be available.

This is 5 inputs and 10 transitions per machine cycle.

Three other useful signals from the machine are AUTO, BYPASS, and over-cycle time limit.

For any line the maximum throughput is achieved when the slow stations are never blocked, and never starved. A TIMELOG monitoring system can help achieve this goal.

Software for the monitoring computer for this application is custom and special order.



Troubleshooting --- semi-permanent or temporary installation on a machine.

Monitor several functions on a single station for time study, troubleshooting intermittent problems, machine or part program development, or studying process timing variance. The monitoring computer can be remotely located and thus unobtrusive.

This involves connecting interface modules 24 v and/or 120 v to the selected machine points. The input interface modules are connected to the TIMELOG module which in turn is connected to a computer. In this application the input modules could be permanently or semipermanently connected to the machine, and the TIMELOG module moved from machine to machine.

A software package TIMCOL16 is run on the PC under PC or MS DOS to collect data.

One time we solved a problem in about two days that the electricans had been working on for over a month. This was not a reflection on their capability, but rather a problem that was very hard to see and might occur once every few hours. It was an intermittent PLC I/O module in a very complex machine cycle.

If you are looking for intermittent problems, then both the TIMELOG module and the PC should be connected to an uninterruptable power supply (UPS).

Initial optimization of a machine is a useful function of TIMELOG.




Betatronics®

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