RS-232 communications

Dear,
Xray machine is communicating with the PLC using RS422communication, some of the addresses are being read by the PLC, other addressesare not read, when we checked the pattern of the sent addresses using a scanneron the XRAY machine, it was noticed that some addresses are being repeatedon a later stages, please refer to attached, so ID's 41, 42, 43, 44 and 45 (C=K is check sum, ID startsafter the letter N) are properly read by the PLC however, ID 46 in yellow isnot read by the PLC since it is followed by repeated old ID's (ID-10), any ideawhy old ID's are being repeated?

is this a communication issue, echo is happening?

any thought on this subject are really appreciated

Forum comments:

If possible, please use a Screenshot instead of a photograph of your screen. Even using Alt-Printscreen and pasting into Microsoft Paint, or using the Snipping Tool built into Windows, will give a clearer and faster-downloading *.BMP or *.PNG file for people to read.

If your data is in an Excel or Word document, it can just as good to ZIP and attach it.


Application questions:

What make and model of PLC are you using ? Does it have a built-in serial port or an expansion module or a network gateway ?

What make and model of X-Ray machine controller are you using ? Can you provide details on its serial protocol or a link to its serial protocol manual ?

Is this a system that you are installing for the first time, or has it been operating for a while and you are troubleshooting it ?

How are you capturing the data ? Do you have a version of the data capture that has timestamps ?


Protocol comments:

This looks like a proprietary ASCII-based serial protocol, rather than something common like Modbus. The incrementing of ID numbers is probably part of the logic in the PLC.

Ken Roach said:

Forum comments:

If possible, please use a Screenshot instead of a photograph of your screen. Even using Alt-Printscreen and pasting into Microsoft Paint, or using the Snipping Tool built into Windows, will give a clearer and faster-downloading *.BMP or *.PNG file for people to read.

If your data is in an Excel or Word document, it can just as good to ZIP and attach it.


Application questions:

What make and model of PLC are you using ? Does it have a built-in serial port or an expansion module or a network gateway ?

What make and model of X-Ray machine controller are you using ? Can you provide details on its serial protocol or a link to its serial protocol manual ?

Is this a system that you are installing for the first time, or has it been operating for a while and you are troubleshooting it ?

How are you capturing the data ? Do you have a version of the data capture that has timestamps ?


Protocol comments:

This looks like a proprietary ASCII-based serial protocol, rather than something common like Modbus. The incrementing of ID numbers is probably part of the logic in the PLC.

Click to expand...

PLC used is Siemens S7-400
Xray machine is L3 MVT - standard 2
the output of the machine is RS232, it is converted to RS422 and fed into the PLC, the scanner which is reading the data coming from the XRAY machine is placed between the RS232 connector and the RS232/RS422 passive converter in order to take data real time.

the data read are from the SCANNER connected to the XRAY, for ID-46, no data is provided on PLC, but for ID-41 up to ID-45 data is read, since it is matching the address requirements (24 characters).

I don't have data with timestamps.

Is your job to connect this EDS with BHS or with analyst station?
I presume that you need to integrate it with BHS.

My job is to integrate EDS with BHS PLC, the scanner is only used for diagnostic purposes.

"Protocol" for integrating EDS in BHS is very complex and it is defined by the EDS producer and you should ask him for manual. When I say protocol I do not mean Modbus, Profibus, Profinet, etc but how is information exchanged between BHS and EDS (what, when and how). We can presume that BHS PLC will be master and that EDS is slave. We can presume that EDS will send you some infeed bag data that BHS had initiated, that it will send exit bag data after EDS screening, and also bag data from level 2 and Level 3 when it happens, also there are some data about state of EDS, analyst station and BHS that are constantly exchanged. Although I never worked with this producer, I can help you, but it is for private mail.

goghie said:

"Protocol" for integrating EDS in BHS is very complex and it is defined by the EDS producer and you should ask him for manual. When I say protocol I do not mean Modbus, Profibus, Profinet, etc but how is information exchanged between BHS and EDS (what, when and how). We can presume that BHS PLC will be master and that EDS is slave. We can presume that EDS will send you some infeed bag data that BHS had initiated, that it will send exit bag data after EDS screening, and also bag data from level 2 and Level 3 when it happens, also there are some data about state of EDS, analyst station and BHS that are constantly exchanged. Although I never worked with this producer, I can help you, but it is for private mail.

Click to expand...

dear Goghie,

This is my email address [email protected]. please send me a test email from your side, thank you
Charbel

Also yesterday we did another test to check connectivity between the BHS PLC (siemens) and L3 screening machine

I have checked the PtP communication modules, they had 2, one for COM1 and one for COM2, what we are interested is the one for COM2 since there is a problem for receiving L2 decision from the screening machine so PtP related to COM2 was having its Rx receiving data (blinking) when the bag was passing through the XRAY machine however, these same data were not receiving in the PLC, might it an data overflow issue?

Intermittent problems with serial communications are frequently due to problems with the wiring that can be due to various causes, : an inadequate cable, poorly shielded, passing through an area with strong electromagnetic interference, too long distance for the selected baud rate, in the case of RS-485 or RS-422 missing resistors at the ends ... etc.

Thank you for you reply lfe, but I don't think that there is a problem with the communicating cables, since we have check the Rx Tx communication on both COM1 and COM2.

thanks,

Charbel

Just a few thoughts fr you
I assume that photo you posted is the raw data coming in on the serial port
The addresses you are looking for 041 – 048 the search for address start would be “N” and ending would be “-“ the address would be the 3 characters long
You are reading the data string in to the plc and you are trying to sore the data from 8 addresses to tags
41,42,43,44,45,46,47,48

But only addressed 41 - 45 are stored in the tags and address 45 – 48 are not

You have not posted the plc code so I can only guess and give you something to think about
It looks to me like in the plc code you are only striping out and storing addresses 41 - 45 and all the other data in the string id just dropped
Look for a search of the incoming string for the saved addresses and see how thatÂ’s handled I would thing you are not searching for the other 3 address to save them
Is it possible that addresses 46 – 48 were added later and fully incorporated in the code ?

It looks like the date string received is a normal ASCII string you have to find the data you want and pull it out then save it to a tag.
Good Luck

Dear

I got update on this issue, the PtP communication module is sending overflow error, error 8088. However, when the buffer size is increased, problem is still not solved. Any idea on this issue? The data shown above are data measured by the scanner of the screening machine.