Different sensors are used depending on the application, the tachometer is independent of my control system, they usually come with an NPN NO induction sensor which is triggered by a magnet. They are also sensitive to the polarity of the magnet, so you need to check that you have a N-S orientation to the sensor. This can be checked by powering up the tach/NPN sensor and running the magnet across the sensor, in the correct orientation the red LED in the sensor should flash when the magnet runs in front of the sensor. The sensors I use for back gear and auto-reverse are PNP NO shielded proximity sensors which sense metallic objects, there are many different types and sensing ranges. I am using them as a non-contact switch, in the case of the auto-reverse it is a small square shielded sensor with a 3mm sense range. This triggers a relay which reverse the F/R VFD inputs using 2 wire control.
On the schematic I have several versions, so send me your current email via PM and I will send you updated schematics and parameters. The one you have is based on 3 wire control of the WJ200 VFD but are dated. As wired with P24, the VFD 24VDC input power supply is powering the LED indicator lights in the switch, so no external power supply is needed. A 3 way switch is used for the direction with the center being off. This is fairly typical of the way most mills work. When you use VFD input 4 programmed for USP unattended start protection, the direction switch must be in the stop position when the machine is powered up otherwise the run command will not work. Cycling the switch through the stop position once powered also does the same thing. If you use the schematic without input 4 then you can use a 2 way F/R switch. Typically most mills with VFDs also have a separate safety start button that will only power up a latching run relay/contactor when the run direction switch is in the stop position.
The diode in the schematic is such that there is both a sustained reverse command and also powers the run/stop inputs. The diode band end is connected to the F switch block. The purpose of the diode is to prevent back feed when the switch is in the F position. An alternative would be to use an extra switch block on the switch, but then it would require a bigger control box because of the stack height of two switch blocks needed for reverse and run command.
There may be a bit of confusion as to the E-Stop, you already have a Stop button on the control pod, I use a unguarded momentary red button for the stop and a guarded green momentary button for run. So in a panic stop you just bang on the red momentary stop button, the E-Stop on the head is redundancy for the stop function, but is in addition a locking off out button for the VFD run controls. This is typically a push, and twist to release type E-Stop. On my mill it came with a digital head which had the F-S-R switch already in the head, on my builds I put that switch in the lower control pod. My mill is an amalgam of the stock VFD system fused with a new control system and I have automatic reverse and auto start based on sensors on the head, in addition to the back gear.
I do find having the run buttons as momentary and down at around the table height, that you will more often turn the motor on/off frequently when doing operations then leaving it running with the typical controls on the head. With the typical non-VFD switch is is very clunky to constantly turn the switch ON/OFF/Reverse, this can lead to being more careless and safety issues if one is not careful.
Lower control pod on my mill.
Upper control pod on my mill.
Stop, Run, F/R, Auto Reverse, Coolant. The enclosure is only deep enough for a single set of switch blocks.