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Cypress OTT-2100 Manual - OSDP Terminology
This section lists and defines in general terms OSDP terminology used in this manual.
Access Control Unit (ACU):
Typically the access controller, the ACU is the device on the OSDP bus that
controls the PDs. The ACU only sends commands to the PDs and waits for replies.
Peripheral Device (PD):
Typically a reader, but many other devices can be PDs, any device on the OSDP
bus that is not the ACU. PDs receive commands from the ACU and send replies.
Address:
OSDP Peripheral Devices are assigned an address, all PDs on the OSDP bus must have a unique
address. This address is used in commands from the ACU and in replies from the PD to indicate which
device the message is being sent to/from.
Baud Rate:
Data transfer rate, expressed in bits per second.
Secure Channel Base Key (SCBK):
16 byte key set by the user used to initiate Secure Channel
communication sessions.
Secure Channel Session:
OSDP communication sessions using the Secure Channel Protocol, which,
among other things, encrypts the data payload in OSDP messages.
Clear Channel Session:
OSDP communication sessions without data payload encryption.
FILETRANSFER:
OSDP protocol used to transfer a file from the ACU to the PD. In the case of the
OTT-2100, a firmware file.
NAK:
Negative acknowledge reply from the PD. Indicates the PD had an error processing the previous
command.
ACK:
Positive acknowledge reply from the PD. The PD properly processed the previous command or
nothing to report to ACU.
RAW:
PD reply with card data payload. Card data is a raw string of bits.
