From: rearman <rearman@r717.net>
Date: Tue, 26 Aug 2025 16:33:33 +0000 (-0400)
Subject: Add wrapper to scale to convert signals to counts
X-Git-Url: https://git.earman.xyz/?a=commitdiff_plain;h=5fad6fd9268a101179f51d0ccc26f2aeac14f040;p=emacsinit.git

Add wrapper to scale to convert signals to counts
---

diff --git a/re/re-plc-defuns.el b/re/re-plc-defuns.el
index 554bece..b55020e 100644
--- a/re/re-plc-defuns.el
+++ b/re/re-plc-defuns.el
@@ -55,11 +55,24 @@ Converts the amperage to a voltage using `amps->volts',then applies
   "Calculate offset given Divisor and both minimums."
   (- scaled-min (/ raw-min divisor)))
 
-(defun scale (raw-max raw-min scaled-max scaled-min)
-  "Calculate the divisor and offset, given the parameters."
+(defun count-scale (raw-max raw-min scaled-max scaled-min)
+  "Calculate the divisor and offset, from counts and eng values."
   (let* ((div (divisor raw-max raw-min scaled-max scaled-min)))
     (list div (offset div scaled-min raw-min))))
 
+(defun scale (signal-max signal-min engineering-max engineering-min &optional impedance)
+  "Calculate the divisor and offset, from signal and eng values.
+Current signal if `impedance' is not nil, otherwise voltage signal.
+Uses `count-range', which uses `*plc-resolution*' and `*plc-max-voltage*'
+variables."
+  (let* ((rng (if impedance
+		  (count-range (amps->volts signal-max impedance)
+			       (amps->volts signal-min impedance))
+		(count-range signal-max signal-min)))
+	 (pmax (car rng))
+	 (pmin (cadr rng)))
+    (count-scale pmax pmin engineering-max engineering-min)))
+
 (defun final (analog-input divisor offset)
   "Calculate the scaled value of an input."
   (+ (/ analog-input divisor) offset))