diff --git a/src/Config.zig b/src/Config.zig
index a175a2d..17d686e 100644
--- a/src/Config.zig
+++ b/src/Config.zig
@@ -48,8 +48,8 @@ labjack: LabjackConfig = .{
     },
 },
 controller: ControllerConfig = .{
-    .azimuth_input = .{ .channel = .diff_01, .gain_index = 2 },
-    .elevation_input = .{ .channel = .diff_23, .gain_index = 2 },
+    .azimuth_input = .{ .channel = .diff_01, .range = .@"5 V" },
+    .elevation_input = .{ .channel = .diff_23, .range = .@"5 V" },
     .azimuth_outputs = .{ .increase = .{ .io = 0 }, .decrease = .{ .io = 1 } },
     .elevation_outputs = .{ .increase = .{ .io = 2 }, .decrease = .{ .io = 3 } },
     .loop_interval_ns = 50_000_000,
diff --git a/src/labjack.zig b/src/labjack.zig
index 950ae10..f350f7f 100644
--- a/src/labjack.zig
+++ b/src/labjack.zig
@@ -50,7 +50,7 @@ pub const Labjack = struct {
             &id,
             @intFromBool(self.demo),
             input.channelNumber(),
-            input.gain_index,
+            input.gainIndex(),
             &over_v,
             &res.voltage,
         );
@@ -93,7 +93,7 @@ pub const Labjack = struct {
         var gains: [incount]c_long = undefined;
         for (inputs, &in_channels, &gains) |from, *inc, *gain| {
             inc.* = from.channelNumber();
-            gain.* = from.gain_index;
+            gain.* = from.gainIndex();
         }
         var v_out: [4]f32 = .{0} ** 4;
         var over_v: c_long = 0;
@@ -133,11 +133,15 @@ pub const Labjack = struct {
 
 pub const AnalogInput = struct {
     channel: AnalogInputChannel,
-    gain_index: GainIndex = 0,
+    range: InputRange = .@"20 V",
 
     pub fn channelNumber(self: AnalogInput) u4 {
         return @intFromEnum(self.channel);
     }
+
+    pub fn gainIndex(self: AnalogInput) GainIndex {
+        return @intFromEnum(self.range);
+    }
 };
 
 pub const AnalogReadResult = struct {
@@ -207,6 +211,17 @@ pub const DigitalOutputChannel = union(enum) {
 // 7 => G=20 ±1 volt
 pub const GainIndex = u3;
 
+pub const InputRange = enum(GainIndex) {
+    @"20 V" = 0,
+    @"10 V" = 1,
+    @"5 V" = 2,
+    @"4 V" = 3,
+    @"2.5 V" = 4,
+    @"2 V" = 5,
+    @"1.25 V" = 6,
+    @"1 V" = 7,
+};
+
 pub const PackedOutput = packed struct(u4) {
     io0: bool,
     io1: bool,