[kingkong111]

So I am wiring up my home/limit switches and I am uncertain if I need a resistor on the signal wire that connects to the C10 BOB.

In the manual (page 6) it says to use a resistor for the NPN switches, would my hall type switch need this resistor? It goes to ground when triggered.


page 6
http://cnc4pc.com/Tech_Docs/C10R10_USER_MANUAL.pdf


here is the sensor I am using and I am powering with 12v.


Why a resistor in the c10 manual, it just goes to ground? I guess I am missing something here.

thanks!

[roundrocktom]

The resistor is used to limit current through the switch.

with 12V, it recommends 10K resistor
with 24V, it recommends a 25K resistor.

In both cases, you are limiting the current to approximately 1mA. This prevents damaging the control circuit (most like a FET).

What is the part number of the sensor you are using?
Include a link to the part number (I haven't a clue if the sensor with will work with the Bob board without a datasheet on the sensor!)

[kingkong111]

The resistor is used to limit current through the switch.

with 12V, it recommends 10K resistor
with 24V, it recommends a 25K resistor.

In both cases, you are limiting the current to approximately 1mA. This prevents damaging the control circuit (most like a FET).

What is the part number of the sensor you are using?
Include a link to the part number (I haven't a clue if the sensor with will work with the Bob board without a datasheet on the sensor!)

hello, thanks for the reply.

The sensor is a "sinking" Honeywell 1av2a hall sensor.

[roundrocktom]

You should be good.

The 1AV series seems to be obsolete. Can not find a fully datasheet on that device, but "sinking" and 1mA seem fine.

Reason for the sensor needing a pull up resistor is to allow multiple devices to be connected together and only use one input. Resistor pulls the input high, but any sensor can pull the input line down. MACH 3, for example, allows for the X Y and Z to all be wired as Normally Open. When it homes it will see a closure and move back from X home, then repeat on Y, then on Z. In that case only one pull up resistor is needed. [This is shown with two sensors in Figure 5 of the C10 manual]

I do see a 2AV series datasheet, simple device:
http://sensing.honeywell.com/index.php?ci_id=50295

[kingkong111]

You should be good.

The 1AV series seems to be obsolete. Can not find a fully datasheet on that device, but "sinking" and 1mA seem fine.

Reason for the sensor needing a pull up resistor is to allow multiple devices to be connected together and only use one input. Resistor pulls the input high, but any sensor can pull the input line down. MACH 3, for example, allows for the X Y and Z to all be wired as Normally Open. When it homes it will see a closure and move back from X home, then repeat on Y, then on Z. In that case only one pull up resistor is needed. [This is shown with two sensors in Figure 5 of the C10 manual]

I do see a 2AV series datasheet, simple device:
http://sensing.honeywell.com/index.php?ci_id=50295

So, to use the 'sinking' sensor in a pull-down (ground) triggering I would NOT need the resistor?

[roundrocktom]

So, to use the 'sinking' sensor in a pull-down (ground) triggering I would NOT need the resistor?

You need the pull up resistor.

Line will be high (pulled up to 12V via the resistor). When the switch turns on, it pulls the line down to 0V.