488 CONTROLLER
20
As a System Controller, the 488 Controller accepts simple high-level ASCII commands from a serial host. It
interprets these commands and performs the required bus action to bidirectionally communicate with up to
14 IEEE devices. As a Peripheral, the 488 Controller becomes a bus device. It accepts simple high-level ASCII
commands from a serial host and interprets these commands and status to communicate with another IEEE
controller. Applications include computer-controlled automatic test systems. These operation modes are
discussed in
Chapters 4
and
5
.
The IEEE Controller Pass-Thru (RS-232 to IEEE Converter) mode allows a serial host device to send data to
a single IEEE bus peripheral. Applications include interfacing a listen-only or addressable IEEE
printer/plotter to a serial printer port. Refer to
Chapter 6
for more detailed information on the Controller
Pass-Thru operation mode.
The Peripheral Pass-Thru mode is used when interfacing a serial device to an IEEE controller. Data which
is sent by the IEEE controller to the 488 Controller is transmitted out its serial port. Data received from the
serial device is buffered by the 488 Controller until it is read by the IEEE controller. Refer to
Chapter 7
for
more detailed information on the Peripheral Pass-Thru operation mode.
The factory default is the System Controller mode.
Figure 3-12. Switch SW2: Selecting the mode.
3.5 Selecting the IEEE Address
SW3-1 through SW3-5 select the IEEE bus address of the 488 Controller when in the System Controller,
Peripheral and Peripheral Pass-Thru modes. These same switches are used in the Controller Pass-Thru mode
to select the address of the device that will be controlled. (Refer to
Chapter 7
for additional information.)
The address is selected by simple binary weighting, with SW3-1 being the least significant bit and SW3-5 the
most significant. The factory default is address 10.
Listen Only is a special type of Peripheral Pass-Thru operation. In the Listen Only mode the 488 Controller
accepts all data transmitted on the bus, ignoring any bus addressing, and transfers it out its serial port. The
488 Controller is set to Listen Only mode by setting its address to 31. If the IEEE address is set to 31 in the
System Controller, Peripheral, or Peripheral Pass-Thru mode, it is adjusted to address 30.
Switch
Side
View
DOT
1 2 3 4 5 6 7 8
OPEN
Controller Pass-Thru
1 2 3 4 5 6 7 8
OPEN
Peripheral Pass-Thru
1 2 3 4 5 6 7 8
OPEN
Peripheral
System Controller
1 2 3 4 5 6 7 8
OPEN
Содержание 488 Controller
Страница 94: ...488 CONTROLLER 92 9 2 Board Layout Figure 9 1 The 488 Controller s motherboard...
Страница 95: ...93 CHAPTER 9 Theory of Operation Board Layout Figure 9 2 The interface converter s serial I O board...
Страница 102: ...488 CONTROLLER 100 How To Read the Chart Hexadecimal Decimal Equivalent Equivalent ASCII Character Address or Command...
