# convert rs232 to rs485 in BL4S200

**URL:** <https://forums.digi.com/t/convert-rs232-to-rs485-in-bl4s200/16560>\
**Category:** Rabbit Software\
**Tags:** rs232\
**Created:** [April 7, 2016, 4:14pm UTC](https://forums.digi.com/t/convert-rs232-to-rs485-in-bl4s200/16560 "2016-04-07T16:14:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![yang](https://avatars.discourse-cdn.com/v4/letter/y/77aa72/32.png) [@yang](https://forums.digi.com/u/yang)\
**Post date:** [April 7, 2016, 4:14pm UTC](https://forums.digi.com/t/convert-rs232-to-rs485-in-bl4s200/16560/1 "2016-04-07T16:14:24Z")

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I am using BL4S200. I would like to convert one RS232 (3 WIRE) to RS485 port. How can I do it? I got one RS232/RS485 converter, but it doesn’t work. I know one RS485 existing on BL4S200, but I need second RS485 for a slow device. Anybody knows that?

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**Author:** ![petermcs](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@petermcs](https://forums.digi.com/u/petermcs)\
**Post date:** [April 8, 2016, 3:54am UTC](https://forums.digi.com/t/convert-rs232-to-rs485-in-bl4s200/16560/2 "2016-04-08T03:54:28Z")

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I’ve used this one from B&B Electronics in the past with the RCM5700 and the RS232 board from the advanced dev kit to implement BACnet MS/TP over RS485. It does auto switching and can be supplied from an external 12V PSU when no hand shaking lines are available to provide power (3 wire).

[http://www.bb-elec.com/Products/Datasheets/P-9145-rev1\_485SD9TB-4115ds-pdf.pdf](http://www.bb-elec.com/Products/Datasheets/P-9145-rev1_485SD9TB-4115ds-pdf.pdf)

Regards  
Peter