I'll also recommend making the jump to the Propeller as soon as you can. Even directly translating Pbasic to Spin and just using the BS2 library, the machine will be more responsive. (be sure to turn on block highlighting in the Spin tool) Development will be quicker too, the extra speed will postpone the need to optimize your code, while 8 hardware tasks allow you to break the problem into small easily coded/tested tasks. Lawson
Can you elaborate? Are you having a problem downloading the file? The BS2 library doesn't work by itself. It requires a parent object to call the various BS2 methods.
I agree with prof_braino's suggestions in post 7 up to a point. When deciding what to save and what to replace I generally start at the mechanical actuators and work back from there.
In your case it sounds as if this is a hydraulically actuated band saw for large stock. If this is the case then I would start with the rate and force control valves as the control outputs, and I suspect the two pressure sensors you mention would be the inputs that are used to control the valves. Most likely they are strain gauge type pressure sensors. Getting part numbers and manufacturers from these parts and posting them would be a great help.
If the electronics for the control valves and pressure sensors are separate modules they can most likely be re-used. Re-use may even be possible if they are on one or more custom boards, but it may be necessary to design replacement boards.
Once you have drivers for the valves a dac (and possibly an op amp) can drive the valves over the required range. Once the input signals from the pressure sensors have been amplified, attenuated, or otherwise processed to produce a suitable signal they can be read by an adc. At this point all that is missing is the human input, and once that is available the micro can use that and the inputs from the adc to control the rate and force.
In your case it sounds as if this is a hydraulically actuated band saw for large stock. If this is the case then I would start with the rate and force control valves as the control outputs, and I suspect the two pressure sensors you mention would be the inputs that are used to control the valves. Most likely they are strain gauge type pressure sensors. Getting part numbers and manufacturers from these parts and posting them would be a great help..
If the electronics for the control valves and pressure sensors are separate modules they can most likely be re-used. Re-use may even be possible if they are on one or more custom boards, but it may be necessary to design replacement boards.
Once you have drivers for the valves a dac (and possibly an op amp) can drive the valves over the required range. Once the input signals from the pressure sensors.
There is only a 3 to 5 psi between each sensor 203 psi and 205
have been amplified, attenuated, or otherwise processed to produce a suitable signal they can be read by an adc. At this point all that is missing is the human input, and once that is available the micro can use that and the inputs from the adc to control the rate and force.
I will see if when I add more force if the different between get larger I will let you know
There is only a 3 to 5 psi between each sensor 203 psi and 205
I will see if when I add more force if the different between get larger I will let you know
I take it from the first two responses that I guessed right and this is a hydraulically actuated band saw.
The low pressure difference and narrow range of pressure to go from moving down to moving up is typical of this type of equipment. Once the pressure reaches the point where it balances the weight of the saw arm it does not take much of a change to start moving the arm. I suspect that the differential pressure will vary as the speed or force setting varies.
You mentioned an encoder in an earlier post. I wonder if that is there to measure the rate of the saw arm movement. Usually there is some mechanism to do that, and it is usually a pot or optical encoder.
I take it from the first two responses that I guessed right and this is a hydraulically actuated band saw.
The low pressure difference and narrow range of pressure to go from moving down to moving up is typical of this type of equipment. Once the pressure reaches the point where it balances the weight of the saw arm it does not take much of a change to start moving the arm. I suspect that the differential pressure will vary as the speed or force setting varies.
You mentioned an encoder in an earlier post. I wonder if that is there to measure the rate of the saw arm movement. Usually there is some mechanism to do that, and it is usually a optical encoder.
That my guess as well to they are conolling the cut arm
What is the make and model number of the hydraulic proportional valve? Typical amplifiers for these things require a +/-10V command signal. Furthermore, these valves usually have significant spool deadband (is there spool feedback, such as LVDT?).
This could very well have been a closed-loop axis for very good reasons.
You will need to know the range (0 – 300 PSI, 0 – 500 PSI, etc.) and type of output signal (4 – 20mA, 0 – 5V, 0 – 10V, etc) of the pressure transmitters.. The information should be somewhere on the transmitter or part of the full part number.
You will need to know the range (0 – 300 PSI, 0 – 500 PSI, etc.) and type of output signal (4 – 20mA, 0 – 5V, 0 – 10V, etc) of the pressure transmitters.. The information should be somewhere on the transmitter or part of the full part number..
You will also need to know the resolution of the encoder or how many pulses/counts it outputs between the arm being full down and full up
"the analog/power control electronics" has a few of these* .
I get the impression that the original control was quite sophisticated and probably utilized at least one PID loop, possibly two. The encoder could have been used for velocity and position control and the pressure sensor for force control.
I also get the impression that a significant amount of paid man/hours has already been invested in this project.
Is the priority here to create a home-grown solution or to get the equipment back to fully-working order?
I note that the encoder, like most industrial types today, is available with complementary and line-driver outputs to help noise immunity. Does this encoder have this and has this been taken in to account?
As much as I enjoy using the Prop, in this case I would strongly recommend THIS or THIS off-the-shelf solution (either can be configured to suit your requirements). This whole thing could be put to bed in <16 hrs for <$1,000.
........The output signal (4 – 20mA)I think It says 700 psi
The data sheet lists 500 PSI and 1000 PSI ranges but not a 0 to 700 PSI range. I suppose we could figure it out by measuring the output current and comparing that to the reading but it would be best to know for sure. Do you have any of the original documentation for that system?
3000 something
The data sheet lists resolutions up to a maximum of 2540. Is “3000” item 6 of the part number on the encoder or is it a count between the lowest and highest position of the arm?
How would you use these ic chips
I could use them for either input or output signals, but that is not really relevant in this case. It may help to know what they are used for on the existing board, but even that may not be necessary.
What is absolutely essential to know is:
1 - The relationships between the voltage/current applied to the Force proportional valve and the resulting pressure and force on the arm.
2 - The relationships between the voltage/current applied to the Rate proportional valve and the resulting pressure and feed rate of the arm, keeping in mind that the feed rate can be up or down (positive or negative).
3 - The number of encoder steps per unit of distance traveled. I am assuming the encoder is used to measure the distance the arm travels, and that it is in inches per minute or seconds. It would be nice to verify this.
4 – Are there any limit switches and safety or emergency switches on this equipment? At the very least there should be an emergency stop switch that will shut everything off. Safety switches that will prevent operation of the system unless the work area is clear of personnel and limit switches that will stop the blade and arm at the upper and lower limits are also a good idea.
The data sheet lists 500 PSI and 1000 PSI ranges but not a 0 to 700 PSI range. I suppose we could figure it out by measuring the output current and comparing that to the reading but it would be best to know for sure. Do you have any of the original documentation for that system?.
This part is custum made for the company that made this saw
The data sheet lists resolutions up to a maximum of 2540. Is “3000” item 6 of the part number on the encoder or is it a count between the lowest and highest position of the arm?.
I could use them for either input or output signals, but that is not really relevant in this case. It may help to know what they are used for on the existing board, but even that may not be necessary
What is absolutely essential to know is:..
This may not be easy to do because when you do not have the valves set the arm fall very fast but I will try to get some value some time next week
2 - The relationships between the voltage/current applied to the Rate proportional valve and the resulting pressure and feed rate of the arm, keeping in mind that the feed rate can be up or down (positive or negative)..
Yes it is but I not sure if they were doing in inches per seconds or in inches per minute
3 - The number of encoder steps per unit of distance traveled. I am assuming the encoder is used to measure the distance the arm travels, and that it is in inches per minute or seconds. It would be nice to verify this..
All of this is controlled by a PLC that is working with no problems it just the controller for the arm that dose not work right any more
4 – Are there any limit switches and safety or emergency switches on this equipment? At the very least there should be an emergency stop switch that will shut everything off. Safety switches that will prevent operation of the system unless the work area is clear of personnel and limit switches that will stop the blade and arm at the upper and lower limits are also a good idea.
So in essence you will be using the two pressure sensor and the encoder inputs to control the motion and force of the arm. How does the system determine the desired speed and force to use?
So in essence you will be using the two pressure sensor and the encoder inputs to control the motion and force of the arm. How does the system determine the desired speed and force to use?
The company that make this saw will only tell you so much
Here what they have told me
The encoder keeps track of how many inches the cutting arm has moved in so many second [ the amount time to the amount of inches] <....... they have not told me
other than the fact that you set the rate proportioning valve amplifier to 20 inches in travel in a minute setting on the amplifier
The two pressure sensor [I do not know what role they play other that the fact this value are use in the set up]<..... you use the PSI gauge on the port block where the proportional valve are mounted to set the force valve to adj the proportioning valve amplifier you set the proportioning valve amplifier so the arm just slowly gose up and then you stop the arm and then set min setting on the amplifier to 150 psi less
This all I know from what I can out of them that they are willing to tell me
What I need to make sense of how this piece of equipment works is a step by step description of what is done to calibrate or set it up to cut some material. From the few cut off saws I have seen there is a speed setting for the band saw, a feed rate for the arm, and a force or minimum/maximum force setting.
On the oldest one I have seen the operator did this manually on pots and switches according to a list of settings for the material being cut. The newest one had a touch screen that let them select the material and thickness/width of stock to be cut. Keep in mind that I never worked on them. I was getting some stock cut and watched how it was done. I understand how it works in theory but have no actual experience with them so the more information the better.
What I need to make sense of how this piece of equipment works is a step by step description of what is done to calibrate or set it up to cut some material. .
I am using a Basic Stamp to control the saw arm on this saw and it has worked very well so far
I use the proportioning valve amplifier that was there and a Basic Stamp
and basically use this code
' {$STAMP BS2}
' {$PBASIC 2.5}
Green_Led PIN 0
Rate_Value PIN 4
Force_Value PIN 7
temp VAR Byte
laps VAR Byte
run:
DO
HIGH 0
temp = 76 '247 makes the value closed
PWM _Rate Value , temp, 05
'076
'075
'074
'073
temp = 131
PWM _Force Value , temp, 05
'165 makes the arm go UP
'136 makes the arm stop
'134 makes the arm move
'132
'130
LOW 0
LOOP
Comments
There is something wrong with this spin file
Can you elaborate? Are you having a problem downloading the file? The BS2 library doesn't work by itself. It requires a parent object to call the various BS2 methods.
If you do make the change to the Propeller here are some objects which I think would be useful.
Kye's quadrature encoder object.
Kye's PWM object.
In post #3 of my index (see signature) I list some useful Propeller tutorials.
In your case it sounds as if this is a hydraulically actuated band saw for large stock. If this is the case then I would start with the rate and force control valves as the control outputs, and I suspect the two pressure sensors you mention would be the inputs that are used to control the valves. Most likely they are strain gauge type pressure sensors. Getting part numbers and manufacturers from these parts and posting them would be a great help.
If the electronics for the control valves and pressure sensors are separate modules they can most likely be re-used. Re-use may even be possible if they are on one or more custom boards, but it may be necessary to design replacement boards.
Once you have drivers for the valves a dac (and possibly an op amp) can drive the valves over the required range. Once the input signals from the pressure sensors have been amplified, attenuated, or otherwise processed to produce a suitable signal they can be read by an adc. At this point all that is missing is the human input, and once that is available the micro can use that and the inputs from the adc to control the rate and force.
I will do this Monday
I will have look in to this part
There is only a 3 to 5 psi between each sensor 203 psi and 205
I will see if when I add more force if the different between get larger I will let you know
I take it from the first two responses that I guessed right and this is a hydraulically actuated band saw.
The low pressure difference and narrow range of pressure to go from moving down to moving up is typical of this type of equipment. Once the pressure reaches the point where it balances the weight of the saw arm it does not take much of a change to start moving the arm. I suspect that the differential pressure will vary as the speed or force setting varies.
You mentioned an encoder in an earlier post. I wonder if that is there to measure the rate of the saw arm movement. Usually there is some mechanism to do that, and it is usually a pot or optical encoder.
That my guess as well to they are conolling the cut arm
General Purpose Pressure Transmitters
Type A-10
http://www.wika.us/upload/DS_PE_A_10_en_us_16479.pdf
HD2.0 Heavy Duty Optical Encoder
http://www.encoder-technology.com/images/stories/ProductSpecs/hd20heavydutyencoder.pdf
"the analog/power control electronics" has a few of these
[3] LM741
[3] H11F1
[1] 74ATC02PC
[1] 74ATC08PC
[1] 74ATC74PC
[3] DC0808LCN
[1] 82C55AC-2
[1] ADC0808CCN
This could very well have been a closed-loop axis for very good reasons.
Regards,
Mickster
Rate valve set up at 3.00 volts and the force set up at 7.00 volts
I do not fine that these valves have that much deadband
No
What dose this mean <............http://www.macrosensors.com/lvdt_tutorial.html.
Thia could be the case
Here are the current reading cutting two stacks of beams.side by side and 8 beams high on this saw that you ask for
Rate 15.4 volts@ 670 millamps
Force 5.7 volts@ 340 millamps
This is with the Basic Stamp controlling the saw arm and no PWM adj were made on the Basic Stamp
Starts off at <......... 211 psi on cyl reading and on the Reg 202 psi no load on the arm
Cutting two stacks of beams.side by side and 8 beams high <..... 202 psi on cyl reading and on the Reg 202 psi
General Purpose Pressure Transmitters
Type A-10
http://www.wika.us/upload/DS_PE_A_10_en_us_16479.pdf
You will need to know the range (0 – 300 PSI, 0 – 500 PSI, etc.) and type of output signal (4 – 20mA, 0 – 5V, 0 – 10V, etc) of the pressure transmitters.. The information should be somewhere on the transmitter or part of the full part number.
HD2.0 Heavy Duty Optical Encoder
http://www.encoder-technology.com/im...utyencoder.pdf
You will also need to know the resolution of the encoder or how many pulses/counts it outputs between the arm being full down and full up.
"the analog/power control electronics" has a few of these*
[3] LM741 Op amps – could be for input or output signals.
[3] H11F1 – Mosfet output opto-isolator. Several possible uses.
[1] 74ATC02PC, [1] 74ATC08PC, [1] 74ATC74PC. Quad nor, quad nand, and dual flip-flop. *
[3] DC0808LCN - Could not find a data sheet but it is probably a DAC chip. **
[1] 82C55AC-2 – Programmable peripheral interface with 3 8 bit output ports. *
[1] ADC0808CCN 8 bit analog to digital converter. **
* Probably not needed for propeller based system.
** You may want to consider using the MCP3204/8 as the ADC and the MCP4921/2 for the DAC.
The output signal (4 – 20mA)I think It says 700 psi
3000 something
How would you use these ic chips
I also get the impression that a significant amount of paid man/hours has already been invested in this project.
Is the priority here to create a home-grown solution or to get the equipment back to fully-working order?
I note that the encoder, like most industrial types today, is available with complementary and line-driver outputs to help noise immunity. Does this encoder have this and has this been taken in to account?
As much as I enjoy using the Prop, in this case I would strongly recommend THIS or THIS off-the-shelf solution (either can be configured to suit your requirements). This whole thing could be put to bed in <16 hrs for <$1,000.
Regards,
Mickster
The data sheet lists 500 PSI and 1000 PSI ranges but not a 0 to 700 PSI range. I suppose we could figure it out by measuring the output current and comparing that to the reading but it would be best to know for sure. Do you have any of the original documentation for that system?
The data sheet lists resolutions up to a maximum of 2540. Is “3000” item 6 of the part number on the encoder or is it a count between the lowest and highest position of the arm?
I could use them for either input or output signals, but that is not really relevant in this case. It may help to know what they are used for on the existing board, but even that may not be necessary.
What is absolutely essential to know is:
1 - The relationships between the voltage/current applied to the Force proportional valve and the resulting pressure and force on the arm.
2 - The relationships between the voltage/current applied to the Rate proportional valve and the resulting pressure and feed rate of the arm, keeping in mind that the feed rate can be up or down (positive or negative).
3 - The number of encoder steps per unit of distance traveled. I am assuming the encoder is used to measure the distance the arm travels, and that it is in inches per minute or seconds. It would be nice to verify this.
4 – Are there any limit switches and safety or emergency switches on this equipment? At the very least there should be an emergency stop switch that will shut everything off. Safety switches that will prevent operation of the system unless the work area is clear of personnel and limit switches that will stop the blade and arm at the upper and lower limits are also a good idea.
This part is custum made for the company that made this saw
Per inch is 3000 some thing
This may not be easy to do because when you do not have the valves set the arm fall very fast but I will try to get some value some time next week
This may not be easy to do because when you do not have the valves set the arm fall very fast but I will try to get some value some time next week
Yes it is but I not sure if they were doing in inches per seconds or in inches per minute
All of this is controlled by a PLC that is working with no problems it just the controller for the arm that dose not work right any more
http://www.wandfluh.com/fileadmin/user_upload/files/A_Dok/reg_1_13/1_13_62_e.pdf Proportional-amplifier P02
http://www.hydraforce.com/Proport/Prop_html/2-432-1_PV70-35/2-432-1_PV70-35.htmPV70-35 — Spool-Type, 2-Way, Normally Open
http://www.hydraforce.com/Proport/Prop_html/2-900-1_TS10-36/2-900-1_TS10-36.htmTS10-36 — Proportional Pressure Control, Pilot-Operated Relief
The company that make this saw will only tell you so much
Here what they have told me
The encoder keeps track of how many inches the cutting arm has moved in so many second [ the amount time to the amount of inches] <....... they have not told me
other than the fact that you set the rate proportioning valve amplifier to 20 inches in travel in a minute setting on the amplifier
The two pressure sensor [I do not know what role they play other that the fact this value are use in the set up]<..... you use the PSI gauge on the port block where the proportional valve are mounted to set the force valve to adj the proportioning valve amplifier you set the proportioning valve amplifier so the arm just slowly gose up and then you stop the arm and then set min setting on the amplifier to 150 psi less
This all I know from what I can out of them that they are willing to tell me
Encoder keep track of how many inches in 30 seconds
Pressure sensors to keep track of the different in pressure from the cyl and reg when there is no load on the arm
Do you have any other ideas that would be better that what I have
On the oldest one I have seen the operator did this manually on pots and switches according to a list of settings for the material being cut. The newest one had a touch screen that let them select the material and thickness/width of stock to be cut. Keep in mind that I never worked on them. I was getting some stock cut and watched how it was done. I understand how it works in theory but have no actual experience with them so the more information the better.
But here is an update
I am using a Basic Stamp to control the saw arm on this saw and it has worked very well so far
I use the proportioning valve amplifier that was there and a Basic Stamp
and basically use this code
' {$STAMP BS2}
' {$PBASIC 2.5}
Green_Led PIN 0
Rate_Value PIN 4
Force_Value PIN 7
temp VAR Byte
laps VAR Byte
run:
DO
HIGH 0
temp = 76 '247 makes the value closed
PWM _Rate Value , temp, 05
'076
'075
'074
'073
temp = 131
PWM _Force Value , temp, 05
'165 makes the arm go UP
'136 makes the arm stop
'134 makes the arm move
'132
'130
LOW 0
LOOP