creation of one of the first automated jobs
I continue the story about the predecessors of PLCs, and today we will touch on one of the first automated workstations in the country – automated workstations and peripherals for automated verification of sensors.
If you look closely, our device can be called an automated process control system device. Why didn't we do this? The business is new, so we chose the name AWP, which seemed very resonant to us. As for specifics, we used workstations to test pressure and temperature sensors. We began to install exemplary pressure instruments on each collector, and temperature sensors on each heat-cold chamber. They are not shown in the block diagram below so as not to overload it.
Explanations: For inductive sensors, a specialized power supply was installed. The potentiometric sensors were powered from the GN09-01 power source from the automated workstation. It is not indicated on the diagram so as not to overload the circuit and not to show that the voltmeter is powered by 220V AC, and GN 09-01 is connected to the supply voltage through a surge protector to combat interference. The remote control, which duplicated the button on the keyboard that started the countdown of the collector readings, is also not shown. After all, we do not have strictly technical documentation, but a story about the first use of controllers at our enterprise more than 35 years ago.
We will also describe the collectors. This is equipment with which pressure was applied immediately to 16 sensors of one type or 18 sensors of another type. And then, in turn, switching the manual switch, the output of the sensor was switched to the input of the digital voltmeter.
In the case of workstations, the switching board was automatic and controlled by a controller. In the machine, the communication board with the voltmeter initially programmed the voltmeter for the desired operating mode and measurement limit, and also began measuring the readings of a specific sensor with the “Start” signal. This was all done under the control of the controller.
Work progress of automated workstation
We carried out preparatory operations, that is, we screwed the manifold to the workshop pressure line, connected the sensors to the workstation with a harness, including power supply to the sensors, and warmed up the equipment for 15 minutes. Now we measure the zero pressure point. The zero point is when there is no pressure (or it is atmospheric). But we shouldn’t get into the jungle of the difference between absolute and excess pressure. This is not the topic of the article.
I remember a sales professional asking me to explain the difference between gauge pressure and absolute pressure. I tried to explain. But no matter how much I fought, he still didn’t understand anything. I probably didn't explain it well.
So, the progress of the work:
The equipment is warmed up;
The air supply is connected to the manifold, but the air is not yet supplied;
The sensors from the manifold are connected to the workstation by a harness;
The type and rating of the sensor is entered on the controller panel. We set the pressure manually;
Press the “Start” button on the remote control. Sensors from the collector are connected one by one to a voltmeter. Sensor readings at zero pressure are recorded in the controller’s memory;
When the zero point is counted, according to the protocol, using a dial standard pressure gauge, the first point of the forward stroke, and then the entire forward stroke. Then the same operation with reverse pressure. (Let me remind you that the forward stroke of the pressure value of the next point is greater than the previous one, the reverse is the opposite, when it is less. So the manifold is counted based on all pressure points of the forward and reverse stroke);
The controller then calculates the maximum sensor variation and the maximum error. This data is stored in memory and displayed in a protocol (hard copy).
The sensors in this workstation were encrypted with conventional numbers. In the following versions of the workstation, we entered the serial numbers of the sensors. Don't forget. This is just the 80s of the last century. Points with defective sensor readings were highlighted in bold. Here is an example of a verification protocol:
Defective – sensor No. 6 at the zero point of forward motion and sensor No. 2 at the point 60 kgf/m2. The error is noted in the protocol, but the variation is normal. There is no indication in bold. Here's how AWP works in a nutshell. We could have called it an automated process control system installation, but we were embarrassed without automatic pressure supply and automatic recording of serial numbers. And when they did it, they forgot about the name of the automated process control system. So at our enterprise such equipment of our own design is still called automated workplace.
The advantage of automated automated control over manual verification
Reducing the number of personnel.
Reducing the influence of the human factor.
Objective control.
Points 2 and 3 could be combined, but I deliberately separated them. The human factor will be considered as random human errors, and objective control will imply the deliberate action of personnel seeking to pass off a substandard device as a standard one.
The staff, of course, are not fools either. He will not push a device that is known to be defective as good. It will cost you more in the end. But the workers were able to pass off an almost defective device (90% tolerance) as completely usable (70–80% tolerance). Either during the flow they checked this point by pressure or applied a lower pressure, and reported to a friend who recorded the data in the protocol that the value was obviously higher. The magic of numbers, so to speak. Or sleight of hand. An experienced worker knew many gangster tricks on how to turn an almost defective sensor into a supposedly ideal sensor.
Below is an automated workplace similar to ours. Only more elegant. Our workstations had a frame assembled from a serious steel angle. Probably to withstand a nuclear explosion. Well, these are not programmers, but designers from OMA itself (department of mechanization and automation) did their best.
Our workstation, or rather, our workstations, since one central processor had several of them. Several pieces each in cold, warm and normal conditions. Frost, heat and normal conditions are the climatic conditions in which the sensors were tested.
Frost and warmth were provided by large climate chambers. Normal conditions were ensured by workshop climate control. A quarter of the workshop area was allocated for ventilation and refrigeration equipment, which kept the temperature at 18 °C in winter and summer. It was nice to go into the workshop in the summer. It's hot outside, but the atmosphere in the workshop is pleasant and comfortable. Even for the first minute it seemed cold. But then it let go.
And when I was still working in the shop as an electronic equipment regulator, I had to stay on the 3rd shift to thermally cycle the devices. So at 3 o’clock in the morning I had to put on my outerwear. This same climate control turned on and cold air began to blow through the entire workshop. Temperature no more than 10 degrees and strong draft. It’s better to wait in a fur coat and hat while the climate in the workshop gets ready for the working day. Such cases happened to me when I worked in the workshop.
And at the end of the article I remember the printer. Nice printer, worked well. It's a pity these printers soon replaced the capitalist Epsons. This country no longer exists. I mean the GDR. And Robotron printers are still remembered. All formats. From A4 to A1 or A0. I don’t remember what the largest size was called.
We had large Robotrons in the information center, printing some reports. And the employees of the ICT imagined before us that they were the smartest programmers. We OMA employees are no match. Although this was not the case. We knew more than the IVTshnits.
On such an optimistic note, let me finish my story about the first automated workplace or automated process control system at our enterprise.
And at the very end I will provide a copy of the potentiometric sensor test report. He has an individual characteristic. Therefore, instead of the “Error” column, there is a “Span” column. This is the difference between the maximum and minimum sensor readings.
But the conversion stopped the activities of the design bureau. Out of 12 people, there were only 2 of us left. And instead of automating special pressure sensors, we developed an automated workplace, waiting for civilian products – household gas meters.
