RCG: correct dac duotone amplitude

DAC duotone is a straight copy of the ADC duotone signal into a DAC channel. This code takes into account the different bit resolution of the various parts so that DAC duotone amplitude is the same for the various combinations of ADC and DAC.

src/epics/util/lib/Filt.pm

@@ -80,6 +80,13 @@ sub frontEndCode {
 	my ($i) = @_;
         my $calcExp = "// FILTER MODULE";
         if ($::ppFIR[$i] == 1) {
+
+            if ( $::modelrate ne 2 and $::modelrate ne 4 )
+            {
+                die ("Error - The model has a FIR filter in it but has a rate of " . $::modelrate .
+                    "K, only 2K and 4K models support FIR filters.");
+            }
+
            $calcExp .= " (PolyPhase FIR)";
         }
         $calcExp .= ":  $::xpartName[$i]\n";