Griggs, Jon wrote the following:
> Please take the following with a tablespoon of salt... I can't find the reference I was looking for and produced the following from memory.
> Correction would be appreciated...
>
>
> While very hazy, I do remember that two things affect communication.
> The first is total cable length.
> The longer the cable, the more capacitance that has to be driven within a specific time window.
>
> The second is how many instruments are turned on.
> Instruments that are off apply a loading to the bus that is more significant that active instruments (maybe?).
>
> I think the max allowable between any active instruments at any point in the bus is 4 meters (?).
> If there are inactive instruments, I think that maximum active device to device length shortens...
>
> Did I set off anyone's B.S. detector?
>
Nope, but here is the text from an Agilent 82350A manual:
** The recommended method for connecting a GPIB system is a linear arrangement
with the system controller (PC) at one end of the system. However, a GPIB
system can also be connected together in a star, linear and a combination
configuration as long as the total number of devices is <=15 and these
guidleines are followed:
* Minimize cable length as much as possible. All system devices must have
tri-state drivers and must be powered on. Systems with devices not using
tri-state drivers are limited to <250Kbytes/sec. Turning devices on or off
while a system is running may cause faulty operation.
* For operation with data transfer rates <500Kbytes/sec, the total length of all
GPB cables is <= 2 meters times the number of devices connected together, up to
a maximum of 20 meters.
* For operation with data transfer rates >500Kbytes/sec the total length of all
GPIB cables is <=1m times the number of devices connected together, up to a
maximum of 15 meters.
* The length between adjacent devices is not critical as long as the overall
restriction is met. GPIB bus extenders are available that allow operation over
much greater distances.
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> Please take the following with a tablespoon of salt... I can't find the reference I was looking for and produced the following from memory.
> Correction would be appreciated...
>
>
> While very hazy, I do remember that two things affect communication.
> The first is total cable length.
> The longer the cable, the more capacitance that has to be driven within a specific time window.
>
> The second is how many instruments are turned on.
> Instruments that are off apply a loading to the bus that is more significant that active instruments (maybe?).
>
> I think the max allowable between any active instruments at any point in the bus is 4 meters (?).
> If there are inactive instruments, I think that maximum active device to device length shortens...
>
> Did I set off anyone's B.S. detector?
>
Nope, but here is the text from an Agilent 82350A manual:
** The recommended method for connecting a GPIB system is a linear arrangement
with the system controller (PC) at one end of the system. However, a GPIB
system can also be connected together in a star, linear and a combination
configuration as long as the total number of devices is <=15 and these
guidleines are followed:
* Minimize cable length as much as possible. All system devices must have
tri-state drivers and must be powered on. Systems with devices not using
tri-state drivers are limited to <250Kbytes/sec. Turning devices on or off
while a system is running may cause faulty operation.
* For operation with data transfer rates <500Kbytes/sec, the total length of all
GPB cables is <= 2 meters times the number of devices connected together, up to
a maximum of 20 meters.
* For operation with data transfer rates >500Kbytes/sec the total length of all
GPIB cables is <=1m times the number of devices connected together, up to a
maximum of 15 meters.
* The length between adjacent devices is not critical as long as the overall
restriction is met. GPIB bus extenders are available that allow operation over
much greater distances.
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examples of how to do this using SocketWrench on this list, but they all
dealt with ASCII strings. I need to send data that is not ASCII strings. I
have tried SocketWrench using the ReadBytes method, but I can't seem to
figure out how to read back the data array. I initialize a unsigned integer
array and pass it to the method, but when I read it back after the method
completes, the buffer has not changed.
I have also tried using .Net to accomplish this task, but I run into the
same problem using the ReadFrom method.
Can anyone help me out? I am running Vee Pro 7.
Thanks,
Brad Avants
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