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Showing results for tags 'pcom'.
Found 8 results
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Hi, I hope you might help with the following issue: I wrote a simple python library, using the PCOM protcol & pySerial. To test it, I created a script that reads a few Memory Bit operands from a SM-43 via the built-in RS232-USB Bridge. The library and the script work perfectly, accept when it comes to reading more than seven bit operands: I used the online mode to set the MB100-107 to the values : 10101100. While the response comes back intact, ( checksum checks out etc) I'm getting different responses for the same request. The respective bytes in the payload of the response message vary between: 0x3521 0x3523 0x3544 0x3543 0x35cb Note that I made sure that the actual bit values in MB100-107 do not change The response is consistent, as long as I don't change the status of MB107. However, as soon as I'm toggling MB107 on and off again, i get a different response from the PLC afterwards. I also get a different response when I change the read request and then go back to the old read request. The first seven bits do not seem to be affected by this - They show 0x35 consistently. Maybe I overlooked something? Thanks in advance for any hint! Max -
I have inherited a project from an engineer who is no longer with my company. The system is a Vision120 communicating to a pc running windows 95. I am tasked with understanding this older system and start to implement updates. I have figured out 99% of the program and communications that is happening with the PC but there is one Command sent to the Vision 120 from the PC that I don't understand what it is for. PC: /00IDED. PLC: /A00IDVUN2A4500153. The ID Command is not covered in the standard PCOM manual. Is there a more thorough PCOM Manual Some Where? Thank you for any assistance.
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Hello, I have a .net application that connects to a 570 via RS-232 using System.IO.Ports.SerialPort. Normally, it will connect. However, when playing with different baud rates, it sometimes does not connect until I connect the same PC with any Unitronics software (Visilogic or Remote Operator). My question is this: With VIsilogic, it appears that you can define the baud rate to anything in the connection properties and it always connects. How does the controller adapt accordingly? I think "out of the box", the rate is set to 115200. If I change my application to 57600, it failes to connect. But, if I connect using Visilogic @ 57600 it works. I go back to my application and then it works. I am trying to determine what Visilogic is doing that I am not. My connection looks like this: // Connect to the PLC try { string comPort = Properties.Settings.Default.CommPort; int comBdRate = Properties.Settings.Default.CommBdRate; int comTimeOut = Properties.Settings.Default.CommTimeOut; _serialPort.PortName = comPort; _serialPort.BaudRate = comBdRate; _serialPort.DataBits = 8; _serialPort.Parity = Parity.None; _serialPort.Handshake = Handshake.None; _serialPort.ReadTimeout = comTimeOut; _serialPort.NewLine = "\r"; _serialPort.Open(); } catch (Exception) { // Disconnect from the PLC _serialPort.Close(); } Once this executes, I begin sending PCOM commands: try { // Send the message out the serial port. _serialPort.DiscardInBuffer(); _serialPort.WriteLine(message); // Verify the message was received, catch the timeout string response = _serialPort.ReadTo("/A00SBF5"); if (response == "/A00SBF5") { //do nothing, success!! } } catch (Exception) { _connectionLost = true; _serialPort.Close(); return -1; } The _serialPort.ReadTo() catches the timeout (default 1 sec). When that occurs, we assume we lost the connection. Is there something I should be doing to prime the port first? Thanks!
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Hello Everyone, I have a new project that would require me to integrate a V130 PLC into an existing .NET application. Basically I'll need to send a "recipe" to the PLC. This will involve setting a series of values (via serial) to a mix of MB's, and MI's. Then the PLC will run autonomously sending status information, and the .NET application will go into a listener mode and simply act as a terminal. So I'm kicking around the best method to do this, and would appreciate any advice on which would be the best method to go forward: Ideally I'd prefer to use the .NET driver, but I'm not sure it's best suited... Does the .NET driver support events? I would image this would require setting the .net driver off on a thread that simply polls a MB or series of MB's for a state change. The obvious approach is that I could use the PCOM protocol, but that would require a fair amount of coding, over the .NET driver. Another approach would be to simply use the protocol scan and send functions in visilogic and establish my own simple protocol for the back and forth. Are there any others options that would be well suited? Please note, I'd prefer to leave the system as it is today (PC <--(RS-232) ---> PLC). Any thoughts would be appreciated.
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Hello, Is there a way to read/write (send) data between 2 plc's via gprs modem, using pcom? I'm using V130 and Siemens TC65 at both ends Thanks in advance! -
I'm trying to write values and I'm not sure what the binary WRITE message format is, in relation to the READ message format. I couldn't find this answered in the PDF or on the forums yet. I read a summary in the PDF that byte 12 should be changed to 68 and the write values should be appended to byte 32 (which confused me further as that's after the footer checksum). This is what I have for READ: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | 24 25 26 27 28 29 | 30 31 32 stx-------------- id FE 01 00 00 00 cn 00 specific--------- lengt chksm | numbr ot FF addr- | chksm ex What would be the correct format for WRITE?
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Hi there; I need to access MI area of a V1040 PLC through ethernet. I had written a code that communicate with PLC via serial port before for an another project. Now, I am planning to modify my code to run under TCP. At PC side, I am working with Delphi XE2 using Indy TCP client component. I tested these components on my network with another computers and they work properly. At PLC side, I am using socket 1, port #20256 and Protocol is TCP Slave.. (I think these are default settings of socket 1 so I don't need to add a socket init FB to my ladder, am i right?) PLC info mode says that card is initialized and socket is connected. In addition, when I send a PCOM string, RX counter increases which showed on info mode but the most important thing is missing: There are no replies. The string I sent is a valid PCOM message which returns answer while I sent it over serial port and plus 6 bytes of ethernet header at the leading. Can you please help me to figure out where is my mistake? With my best regards
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Hello I want to read data tables from an V350. I know i can do that with the PCOM protocol, which is described (partially) in a document (VisionCommunication.pdf). This document describes how you can read the data, but you have to know the data table structure. I also want to read the data table structure my self. I know the data .NET Unitronics.DataTables.dll can do that, but i need it for another platform (microcontroller, programmed in C/C++). So my question is, is the protocol for reading the datatable structure available and/or is the source code of the Unitronics.DataTables.dll available? Regards, Alex
