CHAPTER 6: IEEE 488 Primer
Device 1
System Controller
Able to Talk,
Listen, and Control
Device 2
DMM
Able to Talk and Listen
Device 3
Printer
Only Able to Listen
Device 4
Frequency Counter
Only Able to Talk
To Other Devices
Data Bus
Data Byte
Transfer
Control
General
Interface
Management
DAV
NRFD
NDAC
IFC
ATN
SRQ
REN
EOI
Figure 6-1. IEEE 488 Bus Structure.
6.3 Send It to My Address
In the previous discussion, the terms “Addressed to Talk” and “Addressed to Listen” were used. These terms require some clarification.
The IEEE 488 standard permits up to 15 devices to be configured within one system. Each of these devices must have a unique address to avoid confusion. In a similar fashion, every building in town has a unique address to prevent one home from receiving another home’s mail. Exactly how each device’s address is set is specific to the device’s manufacturer. Some are set by DIP switches in hardware, others by software. Consult the manufacturer’s instructions to determine how to set the address.
Addresses are sent with universal (multiline) commands from the Active Controller. These commands include My Listen Address (MLA), My Talk Address (MTA), Talk Address Group (TAG), and Listen Address Group (LAG).
55
