Doug53

RS232(DB9)

6 posts in this topic

Do most microplcs have a DB9 (RS232) port?  Even other non Rockwell PLCs.  What is the most common port for communications?  I am a newbe and have a Need toKnow. 

Share this post


Link to post
Share on other sites

Most small logic controllers have a serial port of some kind.    Many modern ones have USB and Ethernet as well.

DB9 is a common form factor for RS-232 ports, but I have seen them implemented in DIN-8 (round) connectors (like on the MicroLogix), and in RJ45 and RJ11 modular connectors, and in mini-USB style connectors.

1 person likes this

Share this post


Link to post
Share on other sites

Ken,

Thanks for the response.  It would seem that most of these microcontrollers or regular PLCs need proprietary software to read and write to them.   If I want to communicate with a PLC would a DB9 or USB be the most common?  I have tried to communicate with an old micro plc at home (micrologix 1761-L20BWB-5A).  I was successful after downloading the software which was another difficult experience in itself.  I got interested in this after seeing articles and books saying that I could use visual basic to read and write to a PLC, but have not been successful at this as it seems most PLCs need a DLL file or driver for the individual plc.   Is this correct?  Or is this the topic of another forum?

Share this post


Link to post
Share on other sites

Allen-Bradley/Rockwell has many PLC controller platforms.  There is no port across the board for all of their platforms, but most utilize Ethernet/IP for connectivity.  Most common depends on the system architecture.  This brochure compares the ControlLogix family, displaying the offering of ports in this family.  http://literature.rockwellautomation.com/idc/groups/literature/documents/sg/1756-sg001_-en-p.pdf

The road is long with users who have tried to bypass the challenge of paid software for SCADA communication with an A-B PLC or A-B PLC programming development.  Companies like Allen-Bradley invest the annual maintenance support contract and software purchase funds into providing purchased technical support and latest software features (and rugged hardware).  

If cheap or free software is the only option on the table, then high hardware cost would also be an issue.  If that is the case, A-B may not be the ideal choice.

 

1 person likes this

Share this post


Link to post
Share on other sites

Your PLC is a MicroLogix 1000, which is supported by the free version of RSLogix 500.

You can use AdvancedHMI to create a PC-based HMI/SCADA.

Since you have the ML1000, you probably won't be able to use RSLogix to be online with your PC while the AdvancedHMI application is talking to the PLC. It's *possible* that they can both talk if your AdvancedHMI program is running on the same PC as RSLogix, but I would be amazed if it worked, since COM ports are typically not able to be shared between programs.

If you go up one level to the ML1100, you get Ethernet/IP communications while still being supported by the free RSLogix 500 software, and you can have multiple things connected to the PLC at the same time.

 

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now