Communication Between PC And Vending Machine Using PC's RS232 Using Virtual COM Port (USB) Cable And Vending Machine's Multi-Drop Bus Port (MDB) Port

[BusVend]

I've disconnected the MDB cable from the first MDB port (MDB1) and connected it to MDB2 on the vending machine. I contacted our vending machine supplier Benleigh Vending and they stated that the switching of connections should be automatic but I can't seem to get a reply from MDB2 when I send a signal from my PC application which is sent from an application using RS232 (USB Virtual COM Port COM7) port to the MDB port on the vending machine. I chose the MDB2 port on the vending machine as MDB1 caused issues with the vending machine operations and the PC running Windows 10 Professional. I searched for a switch on the motherboard but couldn't find one. I'm wondering what I should do?

 

[narkeleptk]

Call tech support for the vending machine company is probably going to be your best chance of sucess, maybe they have some one who can team-viewer in and help you remotely.

 

[Pommie]

Double check in device manager that it is actually com7. Do you get an error message from the software?

Mike.

 

[rjenkinsgb]

I think you will likely find the "MDB" connections are not RS232 (using 12V levels) but balanced line such as RS485 or RS422.

You can get USB-Serial adapters to suit those, but they are less common than basic USB COM Port type adapters.

 

[KeepItSimpleStupid]

For those trying to solve this problem: **broken link removed**

 

[rjenkinsgb]

For those trying to solve this problem

OK, looking though the site there is a user manual for their device, which includes the circuit for the MDB interface.
It appears to actually be a current-loop- type system..

See page 8 of the manual:
**broken link removed**

 

[KeepItSimpleStupid]

rjenkinsgb You can make a PDF link open to a specific page (8) by appending "#page=8"

Non-link
https://www.qibixx.com/fileadmin/user_upload/documentation/QIBIXX_MDB-USB_Interface_MS_Product_Documentation.pdf#page=8

Link open to page 8
**broken link removed**

 

[Visitor]

Pocket post. Sorry!

 

[KeepItSimpleStupid]

?

 

[Visitor]

Oops....must have fat-fingered my phone in my pocket.