Hello
I'm interested in developing a small USB to GPIB adapter that will support IEEE 488.1 implementation
I could find electrical specifications, flow control description, etc
I've seen there some commands like untalk / unlisten, but no "talk" \ "listen" command
This link was useful: IEEE488 HP Tutorial description of the Hewlett-Packard interface bus
What i can't find is how the bus controller selects the active talker and listener - the specific command sequence to specify that device with id 10 is the talker and device id n-m are listeners.
Is this command sequence vendor specific ?
There is an open source hardware GPIB / USB adapter available:
http://galvant.ca/shop/gpibusb/
There is an open source hardware GPIB / USB adapter available:
http://galvant.ca/shop/gpibusb/
I just ordered one from Galvant, although I am not sure if there is any ready to go software that can get me started. I am hoping to do simple remote control of my power supplies and create automated volt/time ramps. Writing custom scripts may be too long a learning curve for me at this time.
import instruments as ik
import time
psu = ik.hp.HP6632b.open_gpibusb('/dev/ttyUSB0', 6)
psu.voltage = 10
psu.current = .1
psu.output = True # Enable output
for i in range(1,10):
psu.voltage = i
time.sleep(1)
I've looked over the one made by Galvant, i keep it as a fold-back option if i'll not end with a working unit
This is pretty easy to do with InstrumentKit + the galvant GPIB USB adapter, provided there is a suitable driver for your PSU. What type of PSU do you want to automate?
Example voltage time ramp on a HP6632b using InstrumentKit on linux:
Get the ieee standard at ieee.org. That is the ONLY document you need.
I just got an HP6653A and planning a few other purchases to eventually work up to GPIB automated production PCB testing. It looks like InstrumentKit is Python so it should not be a problem on a Win7 machine [guessing]
Optocouplers on RX / Tx / RTS / CTS ( HCPL-2601.S )
5V rail decoupling + filtering for the power supply
Isolated power supply brick or a simple 1 transistor flyback / royer ( i still need to decide - royer will require 2 center tapped windings + feedback + extra inductor )
-------- isolation --------
One of the links above has those pdf's - posted by lincoln
i've disassembled my signal generator and it seems the GND rail is connected to the chassis ( thumb size diode bolted directly on the chassis with no insulation). also, the power line earth is also bolted on the same plate
Please Use the proper bus driver chips.
Please Use the proper bus driver chips.
While this can be very useful, those chips are built to drive a full line of 15 GPIB loads. This is exactly what you want if you have one adapter and several instruments : but you also need several expensive, unwieldy cables.
If you have a crude adapter that uses cheap buffers or even the micros own IO pins, it will only drive one or two instruments before the signals become poor. But is that unreasonable ? With a USB microcontroller or even ethernet on each adapter, you might no longer use the parallel cables. It could be cheaper to fit an adapter to every instrument.
Are there any signals that can't be handled correctly if you limit the device to one instrument ?
Please Use the proper bus driver chips.
While this can be very useful, those chips are built to drive a full line of 15 GPIB loads. This is exactly what you want if you have one adapter and several instruments : but you also need several expensive, unwieldy cables.
If you have a crude adapter that uses cheap buffers or even the micros own IO pins, it will only drive one or two instruments before the signals become poor. But is that unreasonable ? With a USB microcontroller or even ethernet on each adapter, you might no longer use the parallel cables. It could be cheaper to fit an adapter to every instrument.
Are there any signals that can't be handled correctly if you limit the device to one instrument ?
Arrgh! No! This is probably exactly the thinking that resulted in so many non-compliant adapters out there.
"several expensive, unwieldy cables"
Actually, HP-IB cables are more or less free, because there are so many floating around. And it's how it's supposed to work. Please use the right driver chips.
Cost difference is not much, and with them you can still use an adapter per instrument if that's preferable.