Trouble receiving inputs over parallel port
- F4br1c4t3D
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I'll add resistors as described and see if that solves my problem.
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- F4br1c4t3D
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The input is already being pulled to 0V on the machine side of the optos when an input is triggered.
I don't see any change on the computer side of the optos. Both the collector and emitter pins read 0v when referenced to ground. The paraport pins on the bob that connect the input signals to the computer are always reading 4.7V. They should be being pulled low when the switch is triggered I'd imagine but no.
Starting to think the optocouplers are just borked. Any other clues about the probelm given the symptoms?
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- tommylight
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If that works, check the BOB. If it does not, change the parallel port card.
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- F4br1c4t3D
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Shorting the input pins to ground didn't result in a signal being received when watching the pins in hal.
Are there any other settings in software, bios or elsewhere that I can check before resorting to new hardware?
Also, it seems unlikely that both these ports were defective, with the same problem of working outputs and broken inputs. I'm guessing I've caused the fault if it is a hardware problem. What could I have done to fry the inputs? So far as I can tell the bob just sinks them to ground when a switch is triggered it doesn't have any way to cause damage to the PC hardware.
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- Todd Zuercher
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Also, it seems unlikely that both these ports were defective, with the same problem of working outputs and broken inputs. I'm guessing I've caused the fault if it is a hardware problem. What could I have done to fry the inputs? So far as I can tell the bob just sinks them to ground when a switch is triggered it doesn't have any way to cause damage to the PC hardware.
Just throwing this in. The PP cable is a 25pin cable with all 25 pins connected have you verified that.?
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- F4br1c4t3D
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"I tried "piping" this signal back in to one of the input pins to see if it would change it's state when I triggered the output but all pins remain active."
Was just clutching at straws when I tried it but it seemed like a logical enough thing. No change is state of the input pins in paraport tester though.Good to know it's actually a viable diagnostic technique though.
I'm pretty certain I've defined the ports correctly I wouldn't be getting step and dir signals to my motors otherwise, right?
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- F4br1c4t3D
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Also, it seems unlikely that both these ports were defective, with the same problem of working outputs and broken inputs. I'm guessing I've caused the fault if it is a hardware problem. What could I have done to fry the inputs? So far as I can tell the bob just sinks them to ground when a switch is triggered it doesn't have any way to cause damage to the PC hardware.
Just throwing this in. The PP cable is a 25pin cable with all 25 pins connected have you verified that.?
Now that's something I've not checked. Just assumed that the cable would be wired 1-1 2-2 etc and all pins would be connected. Are there cables out there that don't have all 25 pins connected to their corresponding pins on the other side of the cable?
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Just throwing this in. The PP cable is a 25pin cable with all 25 pins connected have you verified that.?
Are there cables out there that don't have all 25 pins connected to their corresponding pins on the other side of the cable?
Yes there are.
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- tommylight
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I have one ( a high quality one, mind you) that has only 8 wires plus shielding, and they are wired as 4 and 4 crossed over on the DATA pins. Used for high speed data transfer 20 something years ago, using a DOS software named "FX".
Just throwing this in. The PP cable is a 25pin cable with all 25 pins connected have you verified that.?
Are there cables out there that don't have all 25 pins connected to their corresponding pins on the other side of the cable?
Yes there are.
Back on topic,
In BIOS set it to EPP or ECP, in the ini file after the port address add "out" and check it again. Add "in" and check the pins 2 to 9 as inputs, but most probably it will work.
You can also try "X" instead of IN or OUT, that should give you 4 more inputs on pins 1,14,16,17, if i remember correctly.
Above is valid only for the built in port, some add on PCI cards do not support changing the mode, but some do support it, i know all the ones i have with the NETMOS chip do.
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