Terminators; Possible Problem With Spoll - HP 8112A Operating, Programming And Servicing Manual

Terminators

Note
Possible Problem with
6-20 Programming
HP 8112As with the new firmware (starting with serial number
3. Devices with older firmware will hang up when receiving both
should be avoided when programming devices with old firmware.
Since some controllers cannot (easily) be configured so that they do
not to use CR/LF and EOI as terminator, the EOI line of some older
devices is disconnected.
Users of some non-HP versions of BASIC may experience difficulty in
terminating with CRLF alone, i.e. EOI cannot easily be turned off.
If this is the case, a jumper setting inside the instrument allows EOI
line to be ignored. To set this jumper proceed as follows:
Remove rear feet and top cover
n
Transfer jumper A3W3 at the center of the microprocessor board
n
A3 from the factory setting EOI to position 3.
The HP 8112A (with old and new firmware) does not pull the EOI
line. The device terminates all messages with CR/LF and a space
character.
If the HP 8112A is the only instrument on the bus, the SPOLL
statement may cause the instrument to "hang up".
SPOLL
Either of the following will clear the fault:
1. Use an HP-IB cable of not less than 2m length. Or:
2. Use a user-defined function to interrogate the status byte instead
of the usual SPOLL statement.
In the following program, line 20 causes a syntax error so that a
SRQ is generated. Lines 40 to 130 show how the status byte can be
interrogated with a user-defined function:
10
20 OUTPUT A;"XYZ"
3 0
4 0
50 END
60 DEF FNSpoll(A)
7 0
8 0
9 0
100 ENTER S-code USING "#,B";Stb
110 SEND S,code;CMD 25 UNT
120 RETURN Stb
130 FNEND
A=712
WAIT .05
PRINT "Status byte:",FNSpoll(A)
SEND S,code;UNL MLA TALK H,addr CMD 24