Trying to find a PLC

[3horn]

Looking for a PLC with a operator interface (2 or 4 line LCD by 20 characters) and the ability to change about 3 or 4 parameters.

PLC must be able to supply voltage and recieve voltage signals to/from a resolver and make a calculation as to the position of the resolver (in degrees) based on the millivolt signals received from the resolver.

specs on the resolver: it needs for voltage input...750 to 850 mVAC. It supplies as output (x2, X & Y) 850 to -850 mVAC on each output.

the logic will be to recieve the mV inputs, calculate what the position is, then turn off/on digital outputs (to drive relays) based on the settings keyed in by the operator.

any ideas on PLC's that would do this. really trying to keep the cost down also.

thanks

 

[xyzz]

What resolution do you need for analog signals?

 

[OldPfart]

Most PLCs use 24VDC for the inputs. I think Omron have TTL input cards available but they are 5 volt. They also ahave screens of the type you mention, analogues, fuzzy logic, etc etc.

 

[3horn]

i don't know what resolution i need. Any idea what would be a normal resolution scale for a voltage range like this?

 

[xyzz]

Resolution has nothing with signal value range.
It depends on measurement increments you can afford.
Different brand PLC A/D converter modules may be of 8-10-12-14 bit resolution.
Respecting A/D convertion accuracy and linearity, and also the specific 1 bit error of digital systems, I would decrease the specified resolution by 2 bits.

The convertion time also may be a consideration.

Also, this voltage range most probably will require a signal amplifier.

 

[AGomaa]

For such low voltage look for TC/Voltage input range you can find close range to yours,
Automationdirect has a voltage input modules of 0-1.25 V input with 16 bit resolution. (F0-04THM)
They have interfaces as well.
search their web for full range.

http://www.automationdirect.com

 

[plcsavvy]

Have you considered the use of a programmable cam switch?
This device performs exactly the same function you are trying to emulate. I use the "ElectroCam" line of programmable limit switches. Why reinvent the wheel when you can buy it off the shelf?

best regards, PLCSAVVY

 

[plcsavvy]

As for an inexpensive PLC, I would opt for the Automation Direct DL6 PLC. This unit has an optional 2 X 16 charactER lcd display with keypad, that can be used to display alarms and eneter data.

best regards, PLCSAVVY