Ring Interrupts; Interrupts During Data Transfer; Servicing Of Ring Interrupts - Campbell Measurement and Control Module CR10 Operator's Manual

from enabled peripherals in that they are not
enabled solely by a hardware line (Section 6.2.1);
an SD is enabled by an address synchronously
clocked from the CR10 (Section 6.6).
Up to 16 SDs may be addressed by the CR10.
Unlike an enabled peripheral, the CR10
establishes communication with an addressed
peripheral before data are transferred. During
data transfer an addressed peripheral uses pin
7 as a handshake line with the CR10.
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 address peripherals
which are normally enabled (Figure 6.2-1).

6.3 RING INTERRUPTS

There are three peripherals that can raise the
CR10'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 CR10 is installed at a telephone
to RF base station.
When the Ring line is raised, the processor is
interrupted, and the CR10 determines which
peripheral raised the Ring line through a
process of elimination (Figure 6.3-1). The CR10
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 CR10
addresses the Keyboard Display and RF-SDC to
determine which device to service. (Section 6.6)
After the CR10 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 CR10. The one exception
is that a modem cannot interrupt an active RF-
SDC. 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 and RF-SDC is
blocked when the SDE line is high, preventing it
SECTION 6. 9-PIN SERIAL INPUT/OUTPUT
from interrupting data transfer to a pin-enabled
print device.
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 CR10 requires an Instruction 96
with the appropriate parameter. If the CR10 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:
6-3