Measurement Computing Serial488/4 - Manual (Page 18)

Section 1 Introduction
2.6
Figure 2-4. Pictorial View of the Secondary Addressing Mode
Port 2
Control /
Status
Port 1
Control /
Status Port 3
Control /
Status Port 4
Control /
Status
Port 2
Data Port 1
Data Port 3
Data Port 4
Data
Port Select
Command
(Pn)
IEEE 488
Secondary
Address 00
(command) Secondary Addresses
01 - 04
01
(Port 1) 02
(Port 2) 03
(Port 3) 04
(Port 4)
2.3.1.2 Dual Primary Addressing Mode
When Dual Primary addressing mode is selected,
communications with the Serial488/4 is accomplished by using two
consecutive primary IEEE bus addresses. Th ese addresses are
selected by SW-2 through SW1-5, SW1-1 (the LSB) of the address
is ignored. Of the two addresses specified, the even address is used
in transferring command and status information and
the odd
address is used for serial data transfers. In this mode, control of the
serial ports is multiplexed through the even or command/status
address, with the Port ( Pn) command selecting the desired port.
Serial data transfers are multiplexed through the odd or data
address, again with the Port ( Pn) command selecting the desired
port.
Figure 2-5 illustrates the relationship between the