Sending the MARK at the start of a reply from a PD

[mbratch]

Hello

I would like my PD to send the MARK byte before the SOM for each reply. I don't understand the "legitimate" way to do this in libOSDP. I achieved it by a simple hack (commenting out the MARK disable in the libOSDP code). But I'd like to know the non-hack way to achieve this option. :)

Thank you!

[sidcha]

LibOSDP PD tries to be as flexible as possible by following what it's CP does. If the CP sends a packet with MARK byte, the PD will respond with a MARK byte. This allows maximum interoperability.

And for completeness: a LibOSDP CP always sends packets with MARK byte unless LibOSDP is compiled with OPT_OSDP_SKIP_MARK_BYTE.

[mbratch]

Thank you for the reply. I did notice that behavior when reading through the code. I wasn't sure if there was any kind of standard or expectation regarding whether the mark is used.

I was playing with an STid card reader and discovered it always replied with a mark regardless of what I sent it as a CP. So I wondered if it was a settable option in libOSDP to do so.

No biggy. I am happy with it.

Thanks again!

[sidcha]

The reason why we need to be this "flexible" about the mark byte is because not every commercial CP/PD implements it. And that's because the spec has weak requirements by not having it part of the packet structure but offloading it to a different section about physical characteristics (?) of the bus.

[mbratch]

Makes sense. Thanks!