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Section 6. 9-Pin Serial Input/Output
6-3
6.1.2 Addressed Peripherals
The CR10X is different from other Campbell Scientific dataloggers because it can
address Synchronous Devices (SDs). SDs differ from enabled peripherals in that
they are not enabled solely by a hardware line; an SD is enabled by an address
synchronously clocked from the CR10X (see Section 6.5).
The CR10X can address up to 16 SDs. Unlike an enabled peripheral, the CR10X
establishes communication with an addressed peripheral before data is transferred.
During data transfer an addressed peripheral uses pin 7 as a handshake line with
the CR10X.
Synchronously addressed peripherals include the CR10KD Keyboard/Display,
SM716 and SM192 Storage Modules, SDC99 Synchronous Device Interface
(SDC99), and RF95 RF Modem when configured as a synchronous device. The
SDC99 interface is used to synchronously address peripherals which are normally
pin-enabled (see Figure 6-2).
6.2 Ring Interrupts
There are three peripherals which can raise the CR10X’s Ring line: modems, the
CR10KD Keyboard/Display and the RF Modem configured for synchronous de-
vice communication (RF-SDC). The RF-SDC is used when the CR10X is installed
at a telephone-to-RF base station.
When the Ring line is raised, the processor is interrupted and the CR10X deter-
mines which peripheral raised the Ring line through a process of elimination (see
Figure 6-3). The CR10X raises the CLK/HS line forcing all SDs to drop the Ring
line. If the Ring line is still high the peripheral is a modem, and the ME line is
raised. If the Ring line is low the CR10X addresses the Keyboard/Display and
RF-SDC to determine which device to service (see ‘Synchronous Device
Communication’).
Figure 6-3 Servicing of Ring Interrupts