What is the maximum data rate to be achieved by an RS-485 transceiver to date?

RS-485 is a simple, inexpensive, reliable communications specification. It is a widely used protocol for POS, industrial, and telecom applications. Its wide common-mode range enables data transmission over longer cable lengths and in noisy environments such as the floor of a factory. Also, the high input impedance of the receivers allows more devices to be attached to the lines.

Lots of factors limit the maximum data rate of RS-485, including cable length, cable construction (shielding enhances noise immunity), driver output impedance, receiver input impedance, terminations, driver slew rate, and more.

Poll Question: What is the maximum data rate that has been achieved by an RS-485 transceiver to date?

Top Comments

beacon_dave over 1 year ago in reply to genebren +4

The Digilent RS-485 PMOD module 410-310410-310 I have appears to be rated at up to 16Mbps. Hopefully will be doing something DMX-512 related with it at some stage.
kmikemoo over 2 years ago +3

I have not tried RS-485 on anything other than single pair, twisted, shielded - mostly MODBUS. 24AWG is most common, but have done a few runs of 20AWG. 57,600 bps is the highest speed I've used in the…
mp2100 over 2 years ago in reply to kmikemoo +3

Agreed. 57600 is the fastest I’ve done. So that’s 0.0576 Mbps. But it’s used in a noisy EMF environment so I wouldn’t want to go too fast. And I’m using it for long term monitoring only. I don’t need real…

colporteur over 1 year ago

I'm in the other category, not sure.

My pondering gave question to the thought, speed is not only determined by cable quality and/or length. What about duplex and voltage. As people have pointed out, what about noise.

I didn't think speeds in the Mbps were achievable with the RS-485 protocol but then again I'm not keeping up on the spec's like I use to.
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beacon_dave over 1 year ago in reply to genebren

The Digilent RS-485 PMOD module 410-310410-310 I have appears to be rated at up to 16Mbps. Hopefully will be doing something DMX-512 related with it at some stage.
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genebren over 1 year ago

DMX is 250kbps, based on RS-485 signaling. There are several devices that are advertising 20Mbps and even some at 100Mbps.
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dackdickduck over 1 year ago

Never use max speed. But I have tested over 100m so i choose the answer that farhest
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beacon_dave over 2 years ago

Maxim Integrated were pushing 100Mbps over 10m on Cat5e cable a number of years ago, so I expect someone has just produced something faster ?

"...the MAX22500E achieves an unprecedented data rate of 100Mbps over ten meters of Cat5e cable (and potentially over even longer distances depending on the choice of cable selected)..."
https://www.maximintegrated.com/content/dam/files/design/technical-documents/design-solutions/ds61-rs-485-overcome-the-s…
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mp2100 over 2 years ago in reply to kmikemoo

Agreed. 57600 is the fastest I’ve done. So that’s 0.0576 Mbps. But it’s used in a noisy EMF environment so I wouldn’t want to go too fast. And I’m using it for long term monitoring only. I don’t need real-time communication.
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kmikemoo over 2 years ago

I have not tried RS-485 on anything other than single pair, twisted, shielded - mostly MODBUS. 24AWG is most common, but have done a few runs of 20AWG. 57,600 bps is the highest speed I've used in the real world (industrial). 19,200 is way more common. Almost all of the applications are building management or remote annunciation so speed isn't as big a factor.
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