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488.2
General Send/
Receive System
This function uses the status registers to synchronize the GPIB commands and
return data if a query command was used. The system waits until the command
string has been completed and then checks to see if any data is on the GPIB out
-
put buffer. If so, the data is returned in the Result$ argument and any error code
generated in receiving the data is returned in the Result_Code% argument.
For example: Use 4882SendReceive(0, 13, “O 1”, Result$, Result_Code%) to re
-
turn a reading from the ML2430A Series.
Note that this function is written in “pseudo code” and cannot be executed as is.
Function 4882SendReceive (Board%, Addr%, cmdstring$, Result$, Re
-
sult_code%) as integer
‘
Set up SRE and ESE values first, then process User
’
commands, then do *OPC
cmd$ = “*ESE 49; *SRE 48; ” + cmdstring$ + “; *OPC”
‘
Send the command string
Call DLLsend(Board%, Addr%, cmd$, Len(cmd$), Nlend,
ibsta%, iberr%, ibcntl&)
‘
Wait for either the MAV_bit (Message Available)
‘
or/and the ESB_bit (*OPC)
WaitSRQ(Board, Address, MAV_bit + ESB_bit, stb)
If (stb And MAV_bit) Then
‘
Read the data string out from the ML2430A
Result_Code% = ReadML2430A(Board, Address, Result$)
'
If we did not have the ESB_bit set, wait for
‘
it again (*OPC will set this)
If (stb And ESB_bit) = 0 Then WaitSRQ(Board, Address,
ESB_bit, stb)
End if
‘
Check if anything went wrong by asking for the ESB register
Call DLLsend(Board, Address, “*ESR?”, 5, NLend, ibsta%, iberr%, ibcntl&)
‘
Wait for it to return the data on the output queue.
WaitSRQ(Board, Address, MAV_bit, stb)
ReadML2430A(Board, Address, ESB)
‘
Read the ESB value
‘
Check the ESB for the OPC bit being set
‘
(pending commands complete).
If (Val(ESB) and 1) Then
4882SendReceive = True
'
Everything sent
end if
‘
Now check if anything has gone wrong.
If (Val(ESB) And CMD_ERR_bit) Then
4882SendReceive = Command_Error
ElseIf (Val(ESB) And EXEC_ERR_bit) Then
ML2430A OM 6-131
GPIB OPERATION PROGRAMMING EXAMPLES