Measurement Computing Micro 488/EX rev.2.1 - Manual (Page 141)

Section 5 Command Descriptions
5.71
The DATA, EOI and, CMD sub-commands send data bytes or characters over the
bus. The characters to be sent are specified either as a quoted string ('data') or as
individual ASCII values (char[,char…]). For example, DATA'R0X' sends the
characters R, 0, and X to the active listeners, and DATA 13,&H0A sends carriage-
return and line-feed. Multiple ASCII char bytes may be specified by separating them
with commas.
The EOI sub-command is identical to the DATA sub-command except that the
End Or Identify (EOI) signal is asserted on the transfer of the last character.
The CMD sub-command sends the data bytes with Attention (ATN) is asserted.
This tells the bus devices that the characters are to be interpreted as IEEE bus
commands, rather than as data. EOI is not asserted during CMD transfers. For example
CMD
&H3F is the same as Unlisten (UNL). Note that it is not possible to assert EOI
during the transfer of a command byte because EOI and ATN together specify parallel
poll.
The ENTER sub-command inputs data from the active talker, setup from either a
TALK addr sub-command or a previous ENTER command. Addresses are not
allowed to be specified as options to this sub-command. The ENTER sub-command
will terminate upon detection of a Line Feed (LF) character.
Note that the maximum length of the SEND command, including any sub-
commands, is 127 characters. If large amounts of data must be transferred using the
SEND
command, then multiple SEND commands must be used so that they are each
less than 127 characters long. For example…
PRINT#1,"SEND UNT UNL MTA LISTEN 16 DATA 1,2,3,4,5,6"
is equivalent to…
PRINT#1,"SEND UNT UNL MTA LISTEN 16"
PRINT#1,"SEND DATA 1,2,3"
PRINT#1,"SEND DATA 4,5,6"
In this way, a long SEND command can be broken up into shorter commands.