Renishaw TP-20 Probe Connection
- andypugh
-
- Offline
- Moderator
-
Less
More
- Posts: 23178
- Thank you received: 4860
06 Apr 2021 11:10 #205074
by andypugh
Replied by andypugh on topic Renishaw TP-20 Probe Connection
I have a number of Zeiss probes that also have a significant resistance when closed.
I have forgotten what I did to make them work, quite possibly nothing at all.
500R is quite probably low enough to pull-down a pulled-up GPIO input. Have you tried just wiring it in to see what happens?
Now, if you can tell me how to interface a TP-200 probe....
I have forgotten what I did to make them work, quite possibly nothing at all.
500R is quite probably low enough to pull-down a pulled-up GPIO input. Have you tried just wiring it in to see what happens?
Now, if you can tell me how to interface a TP-200 probe....
Please Log in or Create an account to join the conversation.
- jackdavies
-
Topic Author
- Offline
- New Member
-
Less
More
- Posts: 19
- Thank you received: 4
06 Apr 2021 11:19 #205077
by jackdavies
Replied by jackdavies on topic Renishaw TP-20 Probe Connection
I have not yet tried wiring it in, I am still waiting for some spring contacts to arrive, but yes maybe it will just work and I am over complicating this haha.
However there is a strong benefit of reducing the voltage and current actually applied to the ball and pins in the probe to prevent pitting of the contacts over time. As well as an improvement in trigger repeatability.
Can the Index signal at TB3-13 be used as a 5v input? I have put the connections in the attached schematic on the left.
Thanks!
However there is a strong benefit of reducing the voltage and current actually applied to the ball and pins in the probe to prevent pitting of the contacts over time. As well as an improvement in trigger repeatability.
Can the Index signal at TB3-13 be used as a 5v input? I have put the connections in the attached schematic on the left.
Thanks!
Please Log in or Create an account to join the conversation.
- andypugh
-
- Offline
- Moderator
-
Less
More
- Posts: 23178
- Thank you received: 4860
06 Apr 2021 11:38 #205081
by andypugh
Probably. Though I don't think that you have mentioned which Mesa card you are using.
The circuit shown is "NPN", depending on the interface card you are using you might want to change to "PNP". (quotes because I am using the terms loosely to mean "switch to gnd" and "switch to +V").
Replied by andypugh on topic Renishaw TP-20 Probe Connection
Can the Index signal at TB3-13 be used as a 5v input?.
Probably. Though I don't think that you have mentioned which Mesa card you are using.
The circuit shown is "NPN", depending on the interface card you are using you might want to change to "PNP". (quotes because I am using the terms loosely to mean "switch to gnd" and "switch to +V").
Please Log in or Create an account to join the conversation.
- jackdavies
-
Topic Author
- Offline
- New Member
-
Less
More
- Posts: 19
- Thank you received: 4
06 Apr 2021 11:40 #205082
by jackdavies
Replied by jackdavies on topic Renishaw TP-20 Probe Connection
I am using the 7i76e which switches to +V as far as I know, so NPN would be the right one.
Please Log in or Create an account to join the conversation.
- andypugh
-
- Offline
- Moderator
-
Less
More
- Posts: 23178
- Thank you received: 4860
06 Apr 2021 11:50 - 06 Apr 2021 11:51 #205083
by andypugh
Replied by andypugh on topic Renishaw TP-20 Probe Connection
7i76e is sinking inputs on GPIO.
The encoder inputs are differential, but I don't know about sourcing/sinking in that context.
Adding a differential line-driver to your circuit might be a win.
FIELD I/O
The 7I76 has a 32 input, 16 output isolated field I/O system to support a wide range
of input and output devices. The isolated I/O is intended for low voltage DC control
systems (commonly 24VDC). Inputs are sinking type. That is they sense positive input
voltages relative to field ground. Outputs are sourcing (7I76) or sinking (7I76D) type.
Sourcing outputs supply field power to field ground referred loads. Sinking outputs ground
field voltage referred loads when on
The encoder inputs are differential, but I don't know about sourcing/sinking in that context.
Adding a differential line-driver to your circuit might be a win.
Last edit: 06 Apr 2021 11:51 by andypugh.
Please Log in or Create an account to join the conversation.
- jackdavies
-
Topic Author
- Offline
- New Member
-
Less
More
- Posts: 19
- Thank you received: 4
06 Apr 2021 15:29 #205129
by jackdavies
Replied by jackdavies on topic Renishaw TP-20 Probe Connection
I think a transistor could work here as the grounds are shared, and then I could just input it to a standard input.
arduino.stackexchange.com/questions/508/...circuit-with-arduino
arduino.stackexchange.com/questions/508/...circuit-with-arduino
Please Log in or Create an account to join the conversation.
- andypugh
-
- Offline
- Moderator
-
Less
More
- Posts: 23178
- Thank you received: 4860
06 Apr 2021 15:54 #205136
by andypugh
Replied by andypugh on topic Renishaw TP-20 Probe Connection
There already is a transistor, Q1.
But I think that it would be better if Q1 was between the positive field voltage and a GPIO input. If you changed to LM358 you could run the whole circuit at 24V and (with a few resistor changes) still only have 15mV at the probe contacts.
Will this circuit be at the probe end or the machine end?
But I think that it would be better if Q1 was between the positive field voltage and a GPIO input. If you changed to LM358 you could run the whole circuit at 24V and (with a few resistor changes) still only have 15mV at the probe contacts.
Will this circuit be at the probe end or the machine end?
Please Log in or Create an account to join the conversation.
- jackdavies
-
Topic Author
- Offline
- New Member
-
Less
More
- Posts: 19
- Thank you received: 4
06 Apr 2021 20:08 #205176
by jackdavies
Replied by jackdavies on topic Renishaw TP-20 Probe Connection
Yes that would be perfect, would be best at the machine end. Actual probe is only 13mm dia so not much space to package other electronics haha.
Would you know how to modify the schematic to make that work by any chance?
Thanks a lot!
Would you know how to modify the schematic to make that work by any chance?
Thanks a lot!
Please Log in or Create an account to join the conversation.
- andypugh
-
- Offline
- Moderator
-
Less
More
- Posts: 23178
- Thank you received: 4860
06 Apr 2021 20:49 #205183
by andypugh
Replied by andypugh on topic Renishaw TP-20 Probe Connection
I know just enough electronics to be dangerous, so I would rather not advise.
I don't know if you can just connect a PNP transistor to the +V rail and still have it driven by the op-amp output as shown.
This might help:
electronicsclub.info/transistorcircuits.htm
Based on that I think it would probably work to just move the transistor and swap the type. Breadboard it first?
I don't know if you can just connect a PNP transistor to the +V rail and still have it driven by the op-amp output as shown.
This might help:
electronicsclub.info/transistorcircuits.htm
Based on that I think it would probably work to just move the transistor and swap the type. Breadboard it first?
Please Log in or Create an account to join the conversation.
- dm17ry
-
- Offline
- Elite Member
-
Less
More
- Posts: 180
- Thank you received: 66
07 Apr 2021 02:14 #205222
by dm17ry
Replied by dm17ry on topic Renishaw TP-20 Probe Connection
a while ago i checked the renishaw PI4 probe interface unit - it supplies the probe with 12V limited to 0.5mA. so i think some circuit with a comparator before the optoisolated machine input would be a good idea...
The following user(s) said Thank You: eduard
Please Log in or Create an account to join the conversation.
Time to create page: 0.068 seconds