7i47s documentation verbage (analog i/o)

With respect to the documentation for the 7i47s I would like to (re)confirm the allowable input voltages Vcc+, Vcc- (pins 24,22) for the PWM wiper circuit.

Specifically the documentation says:

Is that meant to read that the absoulte value of the ANALOG- and ANALOG+ reference voltages must be between 5 and 15 volts???

Specifically is ANALOG- == -10VDC && ANALOG+ == +10VDC OK ???

but ANALOG- == -4 VDC && ANALOG+ == +12VDC NOK because ANALOG- is not negative enough ???

or ANALOG- == +3 VDC && ANALOG+ == +10 VDC is NOK because ANALOG- is not positive enough???

Also, if the circuit is isolated, to what ground source are the ANALOG[+-] signals referenced???

Sorry, this part of the documentation is not clear to me.

Can the 7i47s wiper provide deltaV =30V , ie +-15VDC range???

Page 10 of the 7i47s manual v1.1 is missing the spec for line-item (ANALOG+ - ANALOG-)

Thanks
_jC
.

Yes, the voltage between ANALOG+ and ANALOG- must be in the range 5V to 15V (the ends of the "potentiometer" )

So if you want bipolar output (not recommended) maximum range would be -7.5 to +7.5V to stay within the 15V maximum rating

The output is totally isolated from the PC
The only "ground" is the ends of the "potentiometer"
(just like a potentiometer). For the intended unipolar
operation, ANALOG- would connect to the VFDs ground pin,
ANALOG+ to +10V, and ANALOGOUT to the VFDs input

Thanks!

So max wiper deltaV == 15v.

Not so good for the Lenze 490 DC speed controller Its potentiometer rails are at +-15VDC.

Maybe the Lenze has a trimpot?

Otherwise looks like something I need to add to a helper circuit board...

You could also do it with a floating 15V power supply and ground either the +15 or -15 end of the PS with the OPTOs or a relay

PCW wrote:

You could also do it with a floating 15V power supply and ground either the +15 or -15 end of the PS with the OPTOs or a relay

Yeah, I just trying to puzzle that out. Not an EE.

Looks like I need switch both legs of the wiper pot (Vcc+ > Vcc- ), but how???



This has to be an idiom.

If you want to use the exiting (non floating) power supply you need a double pole double through switch/relay
But there are a lot of funny side effects (full speed backwards when disabled is one)

With a floating 15V supply you use a double pole double throw switch or relay to reverse the output (always the ANALOG- and ANALOG out)
this is a standard reversing switch but will only work with a floating supply

PCW wrote:

... lot of funny side effects (full speed backwards when disabled is one)

With a floating 15V supply you use a double pole double throw switch or relay to reverse the output (always the ANALOG- and ANALOG out)
this is a standard reversing switch but will only work with a floating supply

I'm too stupid to figure this out. In the floating circuit, where do I put the other half of the dpdt switch to reverse the sense of the wiper control at the zero-crossing???



thx
_jC

_jC wrote:

PCW wrote:

... lot of funny side effects (full speed backwards when disabled is one)

With a floating 15V supply you use a double pole double throw switch or relay to reverse the output (always the ANALOG- and ANALOG out)
this is a standard reversing switch but will only work with a floating supply

I'm too stupid to figure this out. In the floating circuit, where do I put the other half of the dpdt switch to reverse the sense of the wiper control at the zero-crossing???

thx
_jC

The best solution I can find is a using triple-pole switch. I suppose there is a simular solution for the non-floating case. Can't for the life of me see a double pole switch solution.



Rgds
_jC
.

ikm.digitrax.com/questions/93/DPDT+-+Dou...ow+Electrical+Switch

PCW wrote:

ikm.digitrax.com/questions/93/DPDT+-+Dou...ow+Electrical+Switch

Thanks, but ...

where do I put the other half of the dpdt switch to reverse the sense of the wiper control at the zero-crossing???

Still too stupid to see it. I will reflect upon this.

Need to see what is in the comat relays, and if they can be wired in this way