MODBUS protocol in the SLC 500 BAS-T module

Hi!

Please share the MODBUS protocol code for the subject

Regards

Elaborate.

Welcome to the PLCTalk.net forum community !

The 1747-BAS-T module does not, to my knowledge, support Modbus protocol directly.

The classic BAS module and the "Turbo" BAS-T module were essentially BASIC52 system-on-chip interpreters with a library for the serial ports and the SLC-500 backplane. The instruction set goes back to the Intel 8051 microcontroller from 40 years ago.

The same hardware was used for the general-purpose 1747-BAS and for the special-purpose modules with their own communications protocol libraries, built by Prosoft Technology in California.

Those included the 3150-MCM Modbus serial module for the SLC-500 backplane.

There are modern incarnations of those old modules as well, which Prosoft calls the "Multi Vendor Interface" (MVI) series.

The more detail and context you can provide, the better advice we can give.

Which Modbus ? Ascii or other ? If Ascii then no problem except you will have to write the protocol in the PLC i.e. getting data correctly formatted CRC etc. not a simple task & just use the basic card as the send/receive of the registers, I know somebody that did it (not sure if it was Ascii or RTU), I have done it on S5 525 Coms card but that was 30 years ago.

I very strongly recommend against using a 1747-BAS module to write a Modbus protocol stack when there are modules with a 20+ year history of reliably doing exactly that feature.

Thanks everyone for the answers!

To Ken Roach
- "Welcome to the PLCTalk.net forum community!" - Thank you! Glad to join

I studied the documentation for BAS-T modules. They are available at the enterprise. Nobody will buy others. Don't ask why. This is Russia))) Money is not invested in modernization.

Different types of level and temperature sensors work according to the MODBUS RTU protocol. Installed on oil tanks. Currently connected to 3 Moxa N-Port ports. Then the information is transmitted to the I / O server.
I wished to use SLC500 to exclude the server. But, most likely, I will not have time to write the protocol myself, I will soon quit this company. Therefore, I decided to contact the forum, can anyone have the source code.
BAS-T works with old level sensors. But who did it and when no one remembers. Is it possible to upload the source code from this module?

Long time since I did any but yes, I think all you need is a serial terminal program I cannot remember the steps but it's just like the old way of programming basic with commands like list etc. I seem to remember you have to stop the basic program with a command there may also be a jumper to swap over I'm sure people hear will remember better than me.

parky said:

Long time since I did any but yes, I think all you need is a serial terminal program I cannot remember the steps but it's just like the old way of programming basic with commands like list etc. I seem to remember you have to stop the basic program with a command there may also be a jumper to swap over I'm sure people hear will remember better than me.

Click to expand...

I have an SLC500 & BAS-T for experimentation. I connected to the module using the terminal program and wrote a simple BASIC program. Now we need to take the SLC500 & BAS-T operating at the enterprise out of service somehow and experiment with it.

You're in good shape if you are using a terminal program and starting/stopping the BASIC program on the module.

Because the 1747-BAS and the Prosoft 3150 modules use identical hardware, it is possible to substitute the Prosoft firmware EEPROM chip in an A-B labeled module, which I've seen done a few times, especially overseas where somebody's willing to spend time and trouble instead of money and doesn't worry about support or warranty.

If the module has a Prosoft 3150 firmware, you'll be able to get to the serial console features via the configuration port.

Thanks for the answer!
I will not reflash. It is better to write a protocol. But I won't have time, in a month I will leave this company. Other tasks. DirectLOGIC 205 program to change.

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There is such a song in Russia

Нет, не надо слов, не надо паники
Это мой последний день на Титанике
Вот и вся любовь, снимаю батики
Это мой последний день на Титанике

No. No need for words, no need for panic
This is my last day on the Titanic
That's all love, I take off batiks
This is my last day on the Titanic

Thank you all, I will support the resource, maybe my knowledge will be useful to someone