Wiegand to OSDP retrofits: Anyone else seeing latency issues on existing old wiring?

[sanhaowangluo]

Morning gents,
 

We’ve been pushing hard to migrate most of our commercial clients away from legacy Wiegand and over to OSDP v2 (Secure Channel) for the obvious encryption benefits.
 

However, I'm running into a frustrating real-world issue. In a perfect lab environment, the RS-485 backbone handles the two-way OSDP handshake beautifully. But on actual retrofits—where we are forced to reuse the client's existing, ancient 22/6 untwisted alarm wire—I'm noticing a slight, but perceptible, latency when swiping the card before the door actually fires.
 

It feels like the reader and controller are struggling with packet loss/retries over the degraded cable before finally authenticating the secure channel.
 

I know the textbook says RS-485 is good for 4,000 feet, but what is your actual safe distance limit when pushing OSDP over crappy legacy wire? Do you guys just bite the bullet and pull new shielded twisted pair, or are there any termination tricks (besides the standard 120-ohm resistor) to clean up the signal on old cables?
 

Curious to hear your field experiences.

[al-yeti]

5 hours ago, sanhaowangluo said:

Morning gents,
 

We’ve been pushing hard to migrate most of our commercial clients away from legacy Wiegand and over to OSDP v2 (Secure Channel) for the obvious encryption benefits.
 

However, I'm running into a frustrating real-world issue. In a perfect lab environment, the RS-485 backbone handles the two-way OSDP handshake beautifully. But on actual retrofits—where we are forced to reuse the client's existing, ancient 22/6 untwisted alarm wire—I'm noticing a slight, but perceptible, latency when swiping the card before the door actually fires.
 

It feels like the reader and controller are struggling with packet loss/retries over the degraded cable before finally authenticating the secure channel.
 

I know the textbook says RS-485 is good for 4,000 feet, but what is your actual safe distance limit when pushing OSDP over crappy legacy wire? Do you guys just bite the bullet and pull new shielded twisted pair, or are there any termination tricks (besides the standard 120-ohm resistor) to clean up the signal on old cables?
 

Curious to hear your field experiences.

Blame it on the electrician and don't worry about it lol