Can fixed feed rate overrides be set by PLC input?

[johannes]

Hi,
I understand the Acorn doesn't have analog inputs for a potentiometer, but is it possible to assign a PLC input to a specific feed rate? For instance,
if Input 1 is active: set feed rate to 50%
if Input 2 is active: set feed rate to 25%
if Input 3 is active: set feed rate to 5%
etc.

I could then add a rotary switch such as this to get basic feed rate controls at the operator station:


(I'm building a large CNC router, and have been wanting to add an operator station on the shop floor. This is a dusty environment, and although I have seen the USB options such as shuttle express etc, I have been interested in adding a control station with physical buttons (for cycle start, feed hold, cancel, e-Stop and feed rate overrides).

[suntravel]

Sure this is no problem with simple PLC editing, but if 4 Inputs are used, I would use a 4bit 16 Detent Gray Encoder. This gives you 16 steps feed rate with 4 Inputs.

Uwe

[johannes]

@suntravel, Thanks, that sounds like a great way to solve this.

I'll dig into the PLC programming and see how feasible it is.
But thanks for the quick response

[suntravel]

Could work this way:

Define the 4 Inputs

Code: Select all

FeedBit1 IS INP10
FeedBit2 IS INP11
FeedBit3 IS INP12
FeedBit4 IS INP13

and build logic for 4 bit Gray code

Code: Select all

; Test 4 bit GrayCode for Feedrate - UWE 

IF !FeedBit1 && !FeedBit2 && !FeedBit3 && !FeedBit4 THEN KBOverride_W = 0
IF FeedBit1 && !FeedBit2 && !FeedBit3 && !FeedBit4 THEN KBOverride_W = 20
IF FeedBit1 && FeedBit2 && !FeedBit3 && !FeedBit4 THEN KBOverride_W = 30
IF !FeedBit1 && FeedBit2 && !FeedBit3 && !FeedBit4 THEN KBOverride_W = 40
IF !FeedBit1 && FeedBit2 && FeedBit3 && !FeedBit4 THEN KBOverride_W = 50
IF FeedBit1 && FeedBit2 && FeedBit3 && !FeedBit4 THEN KBOverride_W = 70
IF FeedBit1 && !FeedBit2 && FeedBit3 && !FeedBit4 THEN KBOverride_W = 80
IF !FeedBit1 && !FeedBit2 && FeedBit3 && !FeedBit4 THEN KBOverride_W = 100
IF !FeedBit1 && !FeedBit2 && FeedBit3 && FeedBit4 THEN KBOverride_W = 110
IF FeedBit1 && !FeedBit2 && FeedBit3 && FeedBit4 THEN KBOverride_W = 120
IF FeedBit1 && FeedBit2 && FeedBit3 && FeedBit4 THEN KBOverride_W = 130
IF !FeedBit1 && FeedBit2 && FeedBit3 && FeedBit4 THEN KBOverride_W = 140
IF !FeedBit1 && FeedBit2 && !FeedBit3 && FeedBit4 THEN KBOverride_W = 150
IF FeedBit1 && FeedBit2 && !FeedBit3 && FeedBit4 THEN KBOverride_W = 170
IF FeedBit1 && !FeedBit2 && !FeedBit3 && FeedBit4 THEN KBOverride_W = 180
IF !FeedBit1 && !FeedBit2 && !FeedBit3 && FeedBit4 THEN KBOverride_W = 200

Uwe