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INSTALLATION AND OPERATION
WJ-8718A/MFP
2.4.5.3.3
Management Control Lines
The management control signals manage an orderly flow of information across the
bus.
Three signals, ATN (Attention), REN (Remote Enable), and IFC (Interface Clear) are
g~nerated
by the controller. The SRQ (Service Request) signal is generated by the dev-ice under
control, and the EOI signal is generated by the transmitting device (controller or receiver).
The ATN line indicates how data on the DIO lines is to be interpreted. When ATN
is low, data is read as receiver address data and, when high, as parameter data. The REN and
IFC signals (active low) allow the controller to set and reset the interface system.
The SRQ signal indicates that the device under control requires attention. The EOI
signal indicates the end of a multiple byte transfer sequence.
2.4.5.4
Parameter Data
The full operating status of the receiver is contained in 57 bits of data, stored in
eight 8-bit registers. The data associated with each register is listed in Table 2-15.
Data
transmission follows the required handshake signals. In the command mode, a register must be
addressed before transmission of its data word.
In monitor mode, the addressed receiver
transmits an address header, followed by all bytes of parameter data, in the order listed in
Table 2-19. The command and monitor formats are discussed in detail in paragraphs 2.4.5.4.1
and 2.4.5.4.2.
2.4.5.4.1
Command Data Format
In the command mode (receiver is a listener), three types of data words are
transmitted by the controller:
a receiver address word, a register address word, and a
parameter data word corresponding to the register addressed (Table 2-19).
To clarify the
command data format, the following paragraph contains an example of programming technique
using the Hewlett-Packard 9825A Calculator as the remote control device.
2.4.5.4.1.1
Remote Command Programming
The Hewlett-Packard 9825A is a typical remote control device compatible with the
488-1975 Interface Bus. The calculator converts decimal keyboard entries to a binary code
which is applied to the receiver under control. Table 2-20 lists the binary/decimal conversions
for all receiver parameter data.
The command program is entered on the calculator keyboard as a string of decimal
numbers, separated by commas. For example, assume that a receiver at address 06 is to be
commanded to the following parameters:
Tuned frequency - 12.34567 MHz
Detection Mode - AM
Bandwidth - 1 kHz
BFO Frequency - Not applicable in AM
Gain Mode - Manual
RF Gain - 30
2-26
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