Ring Interrupts; Interrupts During Data Transfer; Servicing Of Ring Interrupts - Campbell CR510 Operator's Manual

Synchronously addressed peripherals include the
CR10KD Keyboard Display, Storage Modules,
SDC99 Synchronous Device Interface (SDC99),
and RF95 RF Modem when configured as a
synchronous device. The SDC99 interface is
used to address peripherals which are normally
pin enabled (Figure 6.2-1).

6.3 RING INTERRUPTS

There are three peripherals that can raise the
CR510's ring line; modems, the CR10KD
Keyboard Display, and the RF Modem
configured for synchronous device for
communication (RF-SDC). The RF-SDC is
used when the CR510 is installed at a
telephone to RF base station.
When the Ring line is raised, the processor is
interrupted, and the CR510 determines which
peripheral raised the Ring line through a process
of elimination (Figure 6.3-1). The CR510 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 CR510 addresses the Keyboard
Display and RF-SDC to determine which device
to service. (Section 6.6)
After the CR510 has determined which
peripheral raised the Ring line, the hierarchy is
as follows:
A modem which raises the Ring line will interrupt
and gain control of the CR510. A ring from a
modem aborts data transfer to pin-enabled and
addressed peripherals.
The CR10KD raises the ring line whenever a key
is pressed. The CR10KD will not be serviced
when the modem or RF-SDC is being serviced.
The ring from the CR10KD is blocked when the
SDE line is high, preventing it from interrupting
data transfer to a pin-enabled print device.
SECTION 6. 9-PIN SERIAL INPUT/OUTPUT
FIGURE 6.3-1. Servicing of Ring Interrupts

6.4 INTERRUPTS DURING DATA TRANSFER

Instruction 96 is used for on-line data transfer to
peripherals (Section 4.1). Each peripheral
connected to the CR510 requires an Instruction
96 with the appropriate parameter. If the CR510
is already communicating on the 9-pin connector
when Instruction 96 is executed, the instruction
puts the output request in a "queue" and program
execution continues. As the 9-pin connector
becomes available, each device in the queue will
get its turn until the queue is empty.
Instruction 96 is aborted if a modem raises the Ring
line. Data transfer to an addressed peripheral is
aborted if the ring line is raised by a CR10KD or RF
Modem configured as a synchronous device.
Transfer of data is not resumed until the next time
Instruction 96 is executed and the datalogger has
exited telecommunications.
The 8 Mode is used to manually initiate data
transfer from Final Storage to a peripheral. An
abort flag is set if any key on the CR10KD or
terminal is pressed during the transfer. Data
transfer is stopped and the memory location
displayed when the flag is set. During 8 data
transfer the abort flag is checked as follows:
1. Comma separated ASCII - after every 32
characters.
2. Printable ASCII - after every line.
3. Binary - after every 256 Final Storage locations.
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