SI8 Owen - pulse counter

Guide to counter SI8 Owen   Dowmload   Sive: 1.3 Mb

§1 Description of the pulse counter Owen SI8

Features:
• Forward, backward or reverse pulse counting;
• Determine the direction and speed;
• Counting the current or total flow;
• Actual units of production;
• Counting time between equipment;
• Measuring the length of processes;
• Three external inputs;
• Load control with two output devices;
• Save results account when power supply;
• Built-in RS-485 interface.

Fig. 1 Impulse counter DA-5 Pepperl + Fuchs

Fig.2 Pulse counter AS-8 Kracht

Fig.3 Pulse counter SI8 Owen

§ Little things mean nothing - they define it!

• Display.
  SI8 -8 small numbers.
  DA5 and AS8 - 5 large digits.
  Small numbers are negative, because the controls in the industrial zone is not always possible to come close.
• Keyboard.
  DA5 - high rubber buttons that are easy to press, even while wearing gloves.
  AS8 - the buttons are hidden under the glass.
  SI8 - button under the film, which is not easy (it is an archaism), should push a pointed finger:)
  Buttons should be large and comfortable or they should not even be seen. (Why look at p.3)
• Access to the programming mode the counter.
  SI-8: simply by pressing PROG.
  DA-5: press P and turn the hold button.
  AS-8: вскрыть окно, нажать и удерживать кнопку
  As you can see, access to the programming mode at SI8 very simple, it lacks. While it may use a password to enter the parameters, but it does not always help. Only SI8 I am constantly confronted with a random input in the programming mode. Managed to shoot down the parameters, even on those counters where there is no operator (ie, random people from the interest pokes her fingers).
• Multiplication coefficient (Display size).
  AS8 and DA5 not dependent.
  SI8 is a catastrophe! make the dependence of the decimal point on the display screen on the position of the decimal point in the coefficient multiplying the input pulse!
  As a result:
  Usually have to cover a black tape or paper unnecessary bits to the right (if you want to get the display size in specified units), with at least 8 digits display, most of it goes nowhere, and the digits to the left begins to catastrophically missed. Or, to be inferred on the display size is not clear dimension (for example, when displaying footage covered conveyor belt instead of meters used polusantimetry). In my opinion, a modern computer should be free to convert input signals to the display. Ie not only scaled and rounded it, and add / subtract a constant. With the SI-8 does not realizovano.Po fact, the designer's own hands had destroyed all the features of its counter (see § 1), except for the forward and reverse accounts in integers (it is surprising that the leadership of the company went with them on a leash!)
• The use of counter flow regimes, as amended. speed etc.
  SI-8 barely fit in these regimes.
  As mentioned above in step 4 we can not enter a given accuracy rate of multiplication, we are constrained communication with the display size on the display.
  There are other problems. For example, we want to display on it engine speed (rpm) And why?. Elementary function for the flow meter. Minimum time flow measurement (ti), which it provided for 1 sec. That is, a frequency meter (turnover / sec ie Hz). Multiply by 60 to get the rpm. The engine usually does from 30-60 rev / sec. As a result, the screen we see rpm, jumping every second steps of ± 60 rpm (who needs a smooth measure?). If you want to smoothly take ti = 10 seconds, but then the data on the display will change every 10 seconds (wait for tire).
  Coming to the issue of flowmeters. All flowmeters are linear only in the center. The edges of the characteristics are always overwhelmed. Therefore, the device displays the flow rate should be able to approximation of the curvature.
  

  Fig.4 The real characteristic of the flowmeter
  

  SI-8 has only two points of the binding characteristics (F and di). Therefore, it displays the data only in a straight line, which begins with the displacement di (the blue lines in Figure 5 with di = 0, see below).

  Fig.5 The simplest approximation of the characteristics of the flowmeter
  

  Figure 5 in red shows the simplest approximation of flow characteristics of three lines (DA5). That is, the counter should have at least three ranges in which you can specify different conversion factors. In SI8 approximation is not possible.
• Data exchange interface RS-485.
  In all the counters, it is present.
  This is a very big plus for SI8 as connecting computers to the PC you programmatically destroy all of its shortcomings. You need to have only a direct indication of input pulses, and all continue to do programmatically output on screen PC.

§3 The protocol SI8 Owen via RS-485

The protocol with the devices Owen   Dowmload    Size: 1285 kb Changed:30.06.2009

Fig.6 Construction of the line RS-485 communication from the leadership of the AC3 Aries

In RS-485 protocol Aries provides the presence of only one lead (master), usually a PC with a program survey of secondary devices. Counters SI8 serve as slaves (slaves), they can not themselves initiate the exchange of data and waiting for the command to request data from the lead. Upon receiving the command data request from a leading computer sends the requested data to the network RS-485. This computer does not check the free or busy line of communication and after about 1.1ms gives the answer. This is a shortcoming of the protocol OWEN, because it may cause conflicts in the communication line. In addition, if you use converter interface in which the transmit / receive data in a communication line is selected signal RTS (AC3 Aries), then there is always a chance not to have time to remove its activity within 1 ms, which leads to loss of integrity of the response from the counter. This is particularly sensitive to the OS XP / Vista where the suspension of your program can significantly exceed the interval of 1ms. Settings latency response in the counter SI8 not. To solve this problem, use the converters interface with automatic transmit / receive (AS3M Aries). I solved this problem with the AC3 closure signal TD to RTS jumper and does not use the RTS signal from the COM port of a PC. With such a connection AC3 begins to work as AS3M. Interestingly, the company has developed ARIES AS3M the same way or not?

Another feature of the protocol Aries (and probably its lack) is the transfer of bytes of information tetrad-character way. That is, each transferred byte is divided into two tetrads, each of which is assigned a predetermined symbol, these symbols are transmitted in a communication line. On the receiving side for receiving bytes of information necessary to properly glue these notebooks.

In addition to the character set for the transfer of tetrads are two marker parcels (frame).
This is a # (code 23hex) which serves to indicate the beginning of a parcel (frame) and the symbol CR (code 0Dhex) end of the parcel.

Fig.7 Structure of the frame protocol OWEN

Before working in the network to set the parameters counter SI8
• ALEn - 8 bit or 11 bit address format device
• Adr - address of the device in the network (it must be unique)
• SPd - rate of exchange in the network RS-485

This shows that you can only read my meter, program the settings on the network can not.
For example to read the meter readings with Adr = 4, should be sent to the network the following premise:
# GKHGSHNJNPHU (CR) in hex format, 23 April 1910 C1 73 79 1E 0D
In response, we get (if you count the zeros) answer:
# GKGKSHNJGGGGGGGGBCD5 (CR) in hex format, April 23, 2004 C1 73 00 00 00 00 BC D5

Fig.8 algorithm for computing the checksum protocol OWEN one byte

A textual description of the algorithm:
• Received a parcel reject cookies and checksum;
• Resets variable checksum;
• Load bytes
• Compare the high-order bits and bytes of the checksum;
• Move the checksum by one digit to the right (with the loss of senior level);
• If in step 4 bits are not equal, then we put a checksum with polynomial functions of XOR (exclusive OR);
• Move the byte by one bit to the right (with the loss of senior level);
• Cycle proceed to step 4 until you check all the bits received bytes;
• Next load the next byte send and repeat p.3-8, has not yet processed all the bytes parcel.;

The question remains for hash-fold parameter name, describe in detail I did not will. OWEN designers here for some reason namudrili. The names of the parameters of the device are written clearly displayed in the ASCII transmission tetra-characters in the ASCII. Why convert ASCII to ASCII. For example the parameter names DCNT-> SHNJ, DSPD-> OVST, DTMR-> UMPS always displayed in the same. Aries offers to the parameter name in ASCII (eg DCNT), put it in dvoychny species is not on the code page to ASCII, and the code page invented OWEN. Then make a hash-convolution of a polynomial 8F57hex the algorithm somewhat different from that presented in Figure 8 and the resulting hash-convolution of the transfer in a notebook-symbols on the table Aries. What caused such a thought process of developers I can not explain, why did not immediately call options as needed to insert into the frame?

You may not use all of these changes to work with SI8, you only need to know what the parcel needs to be sent to each address unit. It's easier to do manually on a sheet of paper than to write algorithms for all these treatments.
You can use the table 3, where the parcels are counted for the first 15 addresses.

After receiving a response from the counter in the data field will be his testimony in a symbolic form. Turn characters into binary tetrads per table 1. The resulting binary number to be transferred to the meter readings according to the data format defined by Owen.

§4 Conclusion