Martel Electronics M2000 - Manual (Page 12)

ed control lines. The rest of the interface messages are sent over the data lines with the ATN
signal true. (All device-dependent and common commands are sent over the data lines with
the ATN signal false.)
An important thing to note about interface messages is that unlike device-dependent and
common commands, interface messages are not sent literally (in a direct way).
IEEE-488 standards define interface messages. Interface messages are handled automatically
in most cases.
Compound Commands
A compound command is two or more commands in a single command line. For example,
the following two commands could be entered individually,
OUT 1 V
OPER
where the M2000 sources 1 V dc, and then goes into operate, or they could be combined
into a compound command,
OUT 1 V ; OPER
using a semi-colon as a separator.
Overlapped Commands
Commands that begin execution but require slightly more time to complete are called over-
lapped commands, because they can be overlapped by the next command before they have
completed execution.
The command graphic Overlapped shows a check for overlapped commands.
You can use the command *WAI to wait until the overlapped command has completed execu-
tion before executing the next command. For example,
OUT 1 V ; *WAI
You can also use the status commands *OPC and *OPC? to detect completion of overlapped
commands. (See "Checking M2000 Status.")
Sequential Commands
Commands that execute immediately are called sequential commands.
The command graphic Sequential shows a check for sequential commands.
The majority of the commands are sequential.
Commands for RS-232 Only
The command graphic IEEE-488 RS-232 indicates RS-232 interface commands.
The IEEE-488 and RS-232 interfaces both send commands to the M2000 as data, except for
those IEEE-488 functions that must be implemented as a message as specified in the IEEE-
488 standards. For example, the RS-232 interface uses the command REMOTE to place the
M2000 in the Remote mode. Although the IEEE-488 interface could also send a command
REMOTE as data, it does not because this is one of the functions that must be implemented
per IEEE-488 Standards. The relationship between these IEEE-488 messages and the equiva-
lent RS-232 emulation is shown in Table 5.
Table 5. Commands for RS-232 Only
IEEE-488 Message [1] RS-232 Equivalent
GTL LOCAL command
GTR REMOTE command
LLO LOCKOUT command
Commands for IEEE-488 Only
The command graphic IEEE-488 indicates commands that are used for the IEEE-488
interface. This is all the commands, except for those used for RS-232 operations. (See
"Commands for RS-232 Only.") All commands are transferred over the IEEE-488 as data,
X
X
X
X
12