Bird Technologies 4421 - Manual (Page 25)

IEEE-488 GPIB Interface
13
Talker-Only Mode
The Bird 4421 can be set up for manual operation while automatically sending
data to an output device (Talker-Only Mode). To do so, turn DIP switch 1 OFF
and cycle the power. TALK will be displayed.
In Talker-Only mode, pressing a button on the meter triggers a measurement.
When the measurement is complete, the information is sent to the bus and
LISTEN turns on momentarily. A listen-only device on the bus, such as a
printer, can read the value. The power meter is then ready to accept another
button press.
Command Syntax
The Bird 4421 accepts two types of commands. General bus commands are
commands, such as Device Clear (DCL), that apply to any IEEE interfaced
device. Device-dependent commands are specific to the 4421.
If an invalid command is sent to the unit, an error condition is placed in the
serial poll byte and the offending command is not executed.
A group of device-dependent commands can be sent as a single string as long
as like command categories are not repeated, for example: “PNFCFDT3TRG”.
This string sets up the 4421 to send no prefixes, read forward dBm, make one
reading on “TRG”, and triggers a measurement.
 Note: Commands can be entered in either upper or lower case.
 Note: Only the last command entered of each category will be exe-
cuted. As a command string is processed by the 4421, each category of
command is stored in a separate location. Two commands of the same
category will be stored in the same location, so that the second will
overwrite and erase the first one.
General Bus Commands
The general bus commands supported by the IEEE-488 interface feature are
listed in Figure 5-5. The syntax for executing general commands varies among
controllers; check the documentation supplied with your controller for the
proper command structure.
Table 5-5 IEEE-488 General Bus Commands
Command Effect on Bird 4421
IDN? Gives product identification
REN Goes into remote mode when next addressed
GTL Cancels remote mode, restores local operation
LLO Locks out local operation
IFC Goes into talker and listener-idle status
DCL Returns to default conditions
SDC Returns to default conditions
GET Triggers reading in T2 and T3 modes
SPE, SPD Puts the status byte on the bus