Dear experts!

- My system include : PLC S7-200 224XP ( 2 port), weighing scale CAS-CI1560A (include RS232), cable PC/PPI, RS232-RS485 converter Autonics, PC ( 01 RS232 port )

- Now I connect weighing scale (RS232) <-- RS232-RS485 converter <-- S7-200 --> PC/PPI --> PC

- I wrote a FREEPORT program to read DATA from weighing but I can't connect PLC weighing scale  ==> it's appeared " checking baud rate, port...."

Can anyone help me, i'm just a newbie , i do not know what's wrong with my connection.....

thanks

Hello,

did you look at SMB description depended to Freeport communication settings in MicroWin HELP? For first you need set correctly your required communication settings - speed/parity/... and also use of Freeport protocol. Also you can check history of this S7-200 conference where are some topics about serial communication with external devices via Freeport protocol. What you've prepared in your code? How you define your RECV buffer?

Update: hope you understand that both devices must have same communication settings like speed, data bits, stop bit, parity set. In this case you need configure your weight device as need and via SMB also PLC as I've explained here.

Duris_I

Hello,

did you look at SMB description depended to Freeport communication settings in MicroWin HELP? For first you need set correctly your required communication settings - speed/parity/... and also use of Freeport protocol. Also you can check history of this S7-200 conference where are some topics about serial communication with external devices via Freeport protocol. What you've prepared in your code? How you define your RECV buffer?

Update: hope you understand that both devices must have same communication settings like speed, data bits, stop bit, parity set. In this case you need configure your weight device as need and via SMB also PLC as I've explained here.

 thanks for your reply 

before posting question in this thread , I also do research in this forum and try to understand how FREEPORT works, I also study from Siemens Tips, try to understand Siemens sample and apply to my program 

- After seeing Siemens sample, I decide to make my program by connecting "hardware" , connect weighing indicator to PLC S7-200 by using RS232 - RS485 converter, and download my PLC program y using PC/PPI cable

- I have already downloaded PLC program to PLC, but when I switch PLC to RUN, an error appeared, " checking baud , connection PORT.."

- So firstly, I want to know can I read weighing value from Indicator to PLC by using converter RS232/RS485 in FREEPORT mode ? did I making correctly diagram, using correctly device? after that study more about  FREEPORT protocol. Am I on the "right" way ?

I would appreciate your advice on this matter ! 

Hello,

check pls weigh manufacturer documentation, there you can find what protocol you need implement. In many cases, weigh systems use ASCII protocol with defined messages, all depends to manufacturer. Also exchange data system can be different, in some devices you need send requests depended to your needs and due this device will answer, on other cases you need only listen on port and wait for incomming messages. Sry but this informations still missing from your side, you've post right infos about freeport implementations so maybe you post info what you know about that weigh functionality. On what device that error message appears? Simply keep that Freeport communication as some user defined messages communication but you need for first configure important settings. This info still also missing. For me is important first to know if weigh device really support ASCII user defined messages or other comm protocol. Due this info you can continue next.

Duris_I

Hello,

check pls weigh manufacturer documentation, there you can find what protocol you need implement. In many cases, weigh systems use ASCII protocol with defined messages, all depends to manufacturer. Also exchange data system can be different, in some devices you need send requests depended to your needs and due this device will answer, on other cases you need only listen on port and wait for incomming messages. Sry but this informations still missing from your side, you've post right infos about freeport implementations so maybe you post info what you know about that weigh functionality. On what device that error message appears? Simply keep that Freeport communication as some user defined messages communication but you need for first configure important settings. This info still also missing. For me is important first to know if weigh device really support ASCII user defined messages or other comm protocol. Due this info you can continue next.

 hi

pls see the attached file, you will find out my connection  diagram & Weigh indicator already support ASCII, 

Hello,

for better understanding (also I'm making tests like this) is better interconnect your PC and weigh via RS-232 ports. In case of not have real RS-232 on PC, use some suitable USB-serial port adapter. Run Hyperterminal PC application or other good serial program, open communication port with same comm settings as are set on weigh (speed, data bits, parity, ...). After weigh is trigered (weighing executed, or some push button need to be pushed), some data will be received to your PC program screen. Check that with presented documentation. Pls pay attention to also control characters that are important for correct handling. This schema you can use everytime prior working with real device and PLC, now also you will teach yourself for important things. Then you can start preparing code for PLC, you will be familiar with comm messages functionality and construction of PLC code can be more easy. Recommend.

Duris_I

Hello,

for better understanding (also I'm making tests like this) is better interconnect your PC and weigh via RS-232 ports. In case of not have real RS-232 on PC, use some suitable USB-serial port adapter. Run Hyperterminal PC application or other good serial program, open communication port with same comm settings as are set on weigh (speed, data bits, parity, ...). After weigh is trigered (weighing executed, or some push button need to be pushed), some data will be received to your PC program screen. Check that with presented documentation. Pls pay attention to also control characters that are important for correct handling. This schema you can use everytime prior working with real device and PLC, now also you will teach yourself for important things. Then you can start preparing code for PLC, you will be familiar with comm messages functionality and construction of PLC code can be more easy. Recommend.

 thanks for your recommendation , I wiil follow your instruction and inform to you the result. 

and also sorry for my English . I'm not good at it well yet

Duris_I

Hello,

for better understanding (also I'm making tests like this) is better interconnect your PC and weigh via RS-232 ports. In case of not have real RS-232 on PC, use some suitable USB-serial port adapter. Run Hyperterminal PC application or other good serial program, open communication port with same comm settings as are set on weigh (speed, data bits, parity, ...). After weigh is trigered (weighing executed, or some push button need to be pushed), some data will be received to your PC program screen. Check that with presented documentation. Pls pay attention to also control characters that are important for correct handling. This schema you can use everytime prior working with real device and PLC, now also you will teach yourself for important things. Then you can start preparing code for PLC, you will be familiar with comm messages functionality and construction of PLC code can be more easy. Recommend.

Hello,

perfect to me, looks ok isn't it? Maybe one disadvantage that you don't see hex representation of each char/byte, then you'll be also see all chars/bytes in received message, now you see only characters from ASCII table which have visible interpretation as chars. Some control characters can be also beep sound f.ex. Try sum all bytes from your documentation how received message looks like. Your control chars are CR and LF and also these must be sum, simply each byte from message format. Try find some other application (hope I remember good Hercules??? application) and use it, there you can see also hex format where you can decode also other chars that are now invisible for you. I'm using my own applications. If you sum all bytes, this number you need define as your receive buffer in PLC program. Look to that MicroWin help for SMB description and check some needed settings, depended to Freeport.

Hi

I have found 1 application name Ultra Serial Port, It can change ASCII - HEX value. Is that what you means?

And also you said "sum" value, and put that value to PLC memory ? I don't get that. Could you please explain this matter to me ? 

Hello,

yes, also good application. Now you can see also control chars, look to RX message for 0D and 0A. Compare this with some ASCII table, look in web for it. With sum of chars/bytes I mean you need know how much bytes you'll have in receive buffer (memory) when weigh sends data. Simply count that number of bytes. This number (you can also add some bytes value little bit higher for sure) you need set in DB block in buffer definition. In S7-200 look to help with SMB description (sugested before) and also to XMT/RCV instructions. I see now some TX message in your picture, what's that? You need send some message to weigh first for receive data? I see also some RX without TX messages...

Duris_I

Hello,

yes, also good application. Now you can see also control chars, look to RX message for 0D and 0A. Compare this with some ASCII table, look in web for it. With sum of chars/bytes I mean you need know how much bytes you'll have in receive buffer (memory) when weigh sends data. Simply count that number of bytes. This number (you can also add some bytes value little bit higher for sure) you need set in DB block in buffer definition. In S7-200 look to help with SMB description (sugested before) and also to XMT/RCV instructions. I see now some TX message in your picture, what's that? You need send some message to weigh first for receive data? I see also some RX without TX messages...

 Hi, thanks for your reply, I will follow step by step:

1. What byte CR and LF use for ?

2. Now, I see that there are 15 bytes in CAS-CI1560A format, is that right ! ( pls see the attached pic)

3. "This number (you can also add some bytes value little bit higher for sure) you need set in DB block in buffer definition" --> Is that OK if weigh scale send 15 bytes but PLC receive more bytes ( 16, 17...) ???

4. I will study to know more about SMB, XMT, RCV block in S7-200

5. You see some TX message in my pic --> that's just my misoperation, I was trying to know how Ultra Serial Port work , and it's appeared ! Now , I'm just want to how to transmit data to S7-200. I will do it later .

tomorrow or Monday I will make PLC code and try to receive data from weigh indicator and inform to you the result.   , I hope I can do it.

Hello

I'm so happy to infrom you that I have just received data from CAS to S7-200 in FREEPORT mode, the data format same as the CAS datasheet... 

The first step is successfull , and now I will learn how to change this ASCII code to the real and apply to my application, connect to printer. My application is Packing weighing scale

Thanks for your support , if possible I will as for your support if there is any problem with my protocol, connect to printer...

Thanks again

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