Hello,
Many thanks. I have been successful in all the steps you mention using the Arduino converter, but I need to activate REN for sending a command and then deactivate REN before reading.?
This is not possible (controlling REN) using 82357 - or is there a way? I’m fairly sure this is the issue with the 436 (REN).
Regards,
?Staffan
On Tuesday, November 20, 2018, Dave_G0WBX via Groups.Io <g8kbvdave=
[email protected]> wrote:
A simple task...
But it is NOT IEE488.2 compliant, so will not respond to such things as
*IDN? etc.? (In fact, traffic like that can totally mess it up at times,
as can other automated tricks to attempt to catalogue "live" devices on
the bus..)
Modern GPIB systems will handle all the global un-listen, selected
device addressing and so on for you, making life much easier.? If you
create your own GPIB controller, you have to do all that yourself.
Make sure you know it's device address on the bus.? Ours is defaulted to
a primary address of '13' (decimal.)??? AFIK (oddly, I cant find the
detail in our manual!)? The address setting is a bank of switches
internally.??? If you need to "scan the bus" to find it, you may need to
manually reset the thing after you know it's address, as it's a simple
state machine in hard logic internally, and can get "upset" by command
data it cant understand.
Anyway, when you know it's bus address...?? And it's Talk Mode is set to
"Normal".
Send it the command '9A+I' (not the quotes!) with no trailing terminator
byte, with or without EOI asserted, it doesn’t care about that.? That
command instructs it to send back a reading scaled in Watts.? (Or '9D+I'
in which case It will scale in dB/dBm.)
Use Watt's initially, as a no input signal condition, will still result
in a valid reading!
Give it a little time to figure things out...
When you then ask the system to read back the resulting "measurement".
The 436A will send a 14 byte fixed format ASCII string to the
controller, ending in a CR/LF pair, so your GPIB system needs to be
configured to stop reading when it sees a LF byte (ASCII code 10, or
0x0A)? The 436A does not use the EOI line, so you MUST configure your
bus controller to recognise that LF byte to signify the end of it's
reply, or to stop reading after 14 bytes have been received.
The first byte (byte 0) is the status. ('P' = valid reading.? Anything
else is under/over range.)
Bytes 3 to 11 represent the measured value, in scientific format (Mantissa).
Byte 3 is a sign (ASCII space = +) or and ASCII -
Bytes 4..7 are the measured value, an implied decimal point is
immediately after byte 7.
Byte 8 is always an 'E'.
Byte 9 is always a - sign.
Bytes 10 .. 11 is the Exponent.
Bytes 12..13 are CR/LF
It's all ASCII characters, so no "funny" stuff.
The above comes from table 3-4 on page 3-25 of the operating and service
manual.
It's up to you to process that string to test for validity, and extract
the value.
It is highly recommended to get a copy of at operator/service manual.?
(I only have a dead tree version.)
Hope this helps.
Dave B (G0WBX)
--
Created on and sent from a Unix like PC running and using free and open source software.
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