You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old April 14th, 2019, 10:07 AM   #1
sandy5020
Member
India

sandy5020 is offline
 
Join Date: May 2012
Location: vadodara
Posts: 72
1746 BAS 502 M0/M1 module

Hi,

I am upgrading a AB PLc to Siemens PLC logic and everything is ready for siemens but the problem is the existing PLC is communicating to DCS via modbus RTU as slave.

I can see some alarms and data from N10:0 register moving to M0:1.1 with a length of 50 file and from DCS M1:1.1 data moving to register N10:22 with a length of 1.

I wish to know the modbus address of this is it like N10:0=40001 and N10:22 = 400022 ?? as I need to do the same in siemens PLC with the help of modbus module

Regards
Sandy
  Reply With Quote
Old April 14th, 2019, 12:46 PM   #2
Ken Roach
Lifetime Supporting Member + Moderator
United States

Ken Roach is offline
 
Ken Roach's Avatar
 
Join Date: Apr 2002
Location: Seattle, WA
Posts: 14,554
The 1746-BAS is an old BASIC52 system-on-chip with a backplane interface and API.

ProSoft Technology used the same hardware to build many of their serial interface modules, including the "MCM" Modbus communication modules. Every once in a while you'll find a module with the 1746-BAS label that has been loaded with the ProSoft MCM firmware.

So Step 1 is to figure out if this is a true Modbus module, or if it's a BASIC module that's implementing Modbus or another serial protocol.

If it's truly a ProSoft module, then you can use their User Manual to determine which M0/M1 buffer addresses correspond to what Modbus registers, based on how the module is configured.

If it's a custom program running on a 1746-BAS, then you'll have to connect with a serial console and LIST the program to read it, then start analyzing that program.
  Reply With Quote
Old April 15th, 2019, 01:50 AM   #3
sandy5020
Member
India

sandy5020 is offline
 
Join Date: May 2012
Location: vadodara
Posts: 72
Hi,

i am sure the protocol is Modbus RTU slave as there is ladder logic in the PLC program for data transfer via modbus.. I just need to know the addressing so that I can do the same with new PLC ie siemens with modbus module

Regards
Sandy
  Reply With Quote
Old April 15th, 2019, 02:43 PM   #4
Ken Roach
Lifetime Supporting Member + Moderator
United States

Ken Roach is offline
 
Ken Roach's Avatar
 
Join Date: Apr 2002
Location: Seattle, WA
Posts: 14,554
I will repeat: the 1746-BAS is not a "Modbus Module". It is a general purpose BASIC52 computer with a backplane interface.

If your is really a Prosoft "MCM" with a label that says "1746-BAS", then you can read the Prosoft user manuals to learn how the module works.

If not, then I cannot tell you how your particular module works, because it must have a custom program in it.

Try this: Go into RSLogix 500 and open the I/O Configuration window.

For the slot occupied by that communication module, does it say "1746-BAS" (or some variation of that) or does it say "OTHER" with a Module ID number ?

That will at least tell us what type of module the controller thinks it's running.

Power down, remove the module, and examine the module very carefully for the ProSoft part number "3150-MCM".
  Reply With Quote
Old April 15th, 2019, 04:36 PM   #5
sandy5020
Member
India

sandy5020 is offline
 
Join Date: May 2012
Location: vadodara
Posts: 72
Hi,

I have checked the IO configuration and It is showing "1746-BAS 5/02 BASIC module M0/M1 capable
Regards
Sandy
  Reply With Quote
Old April 16th, 2019, 08:10 AM   #6
Ken Roach
Lifetime Supporting Member + Moderator
United States

Ken Roach is offline
 
Ken Roach's Avatar
 
Join Date: Apr 2002
Location: Seattle, WA
Posts: 14,554
OK, good.

So we know it's either a true 1746-BAS with custom firmware in it, or it's a Prosoft 3150-MCM with the wrong label. Both of those modules will show the "1746-BAS 5/02 BASIC module M0/M1 capable" in the I/O configuration.

My next step would be to connect to the console port with a serial terminal emulator program (I prefer RealTerm) and see if the module reacts like a Prosoft module or like a BASIC module.

You can read up on how to connect to the console port in the user manuals:

1746-BAS: https://literature.rockwellautomatio...m004_-en-p.pdf

Prosoft 3150-MCM: https://www.prosoft-technology.com/S...0-SLC/3150-MCM
  Reply With Quote
Old April 16th, 2019, 12:45 PM   #7
sandy5020
Member
India

sandy5020 is offline
 
Join Date: May 2012
Location: vadodara
Posts: 72
Hi,

Thanks for the reply, I understand the details should be collected from the module but the problem is machine is running and the customer will not allow to touch the existing one we have already uploaded the program before some months during a major shutdown. I have only two option either to understand the mapping from the RSlogix program or from the DCS program.

My final concern is to map the addressing with siemens s71200 plc as modbus rtu slave, program has been created for the siemens now I just need to copy some tags to modbus for DCS.


Regards
Sandy
  Reply With Quote
Old Yesterday, 07:28 AM   #8
Ken Roach
Lifetime Supporting Member + Moderator
United States

Ken Roach is offline
 
Ken Roach's Avatar
 
Join Date: Apr 2002
Location: Seattle, WA
Posts: 14,554
I have done similar system migrations in the past and had to use a protocol analyzer coupled with the monitoring software in the PLC controller to develop a map of PLC memory to Modbus registers.

If you can't disconnect the RS-232 port for even a few seconds, then it's impossible to put an analyzer in-line with it.

If you can, I very strongly recommend the EZ-Tap from Stratus Engineering in California. It's a passive serial tap that will fit in-line with an RS-232 port and allow you to connect over USB as though each port was a separate Windows COM port. You can use a sophisticated protocol analyzer like Frontline Test Equipment, or decode the Modbus frames by hand or with a helper tool like the Chipkin Automation Module Parser.

To my knowledge the old 3150-MCM modules don't have a runtime console that you can monitor while it's operating.

So to figure out how the module is set up, you'll have to examine the SLC-500 programm in conjunction with the 3150-MCM User Manual.
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
1794-aent module error stallone LIVE PLC Questions And Answers 7 March 6th, 2019 01:00 PM
S7 300 Module Ger_gnu LIVE PLC Questions And Answers 0 January 2nd, 2011 09:28 AM
1746 IO module for thermistor idowulawrence LIVE PLC Questions And Answers 2 April 21st, 2010 11:31 AM
AB 1746-HS module - IMC 110 motion controller raj LIVE PLC Questions And Answers 12 February 20th, 2009 12:36 AM
SLC 5/03 data loss andydaoust LIVE PLC Questions And Answers 1 October 10th, 2002 06:38 PM


All times are GMT -5. The time now is 05:23 PM.


.