diff --git a/main.cpp b/main.cpp
index 0e82aa5..24bceea 100644
--- a/main.cpp
+++ b/main.cpp
@@ -37,6 +37,7 @@ static std::atomic<float> freq_setpoint;
 static std::atomic<float> freq_peak;
 static std::atomic<float> tec_bias;
 static std::atomic<float> tec_p;
+static std::atomic<float> tec_current;
 
 static std::atomic<int> fps;
 
@@ -45,7 +46,7 @@ static void dsp_thread() {
 
     net::io_context io_context;
     net::ip::tcp::socket tec_socket(io_context);
-    tec_socket.connect(net::ip::tcp::endpoint(net::ip::make_address("192.168.1.91"), 5555));
+    tec_socket.connect(net::ip::tcp::endpoint(net::ip::make_address("192.168.1.27"), 23));
 
     size_t len = 16384;
     std::vector<std::complex<int16_t>> frames(len);
@@ -84,10 +85,20 @@ static void dsp_thread() {
             float freq_peak_local;
             freq_peak_local = 40.0f*float(distance(frames_mag.begin(), max_element(frames_mag.begin(), frames_mag.end())))/float(len);
             freq_peak = freq_peak_local;
-            // FIXME: net::write seems unimplemented as of libstdc++ 13
             float freq_error = freq_peak_local - freq_setpoint;
-            tec_socket.write_some(net::buffer(std::format(":SOUR2:VOLT {:.3f}\n",
-                std::max(tec_bias+tec_p*freq_error, 0.0f))));
+            float tec_current_local = std::max(tec_bias+tec_p*freq_error, 0.0f);
+            tec_current = tec_current_local;
+            // FIXME: net::write seems unimplemented as of libstdc++ 13
+            tec_socket.write_some(net::buffer(std::format("pwm 0 i_set {:.6f}\n", tec_current_local)));
+            std::string reply;
+            net::read(tec_socket, net::dynamic_buffer(reply),
+                [&reply](auto ec, auto n) -> std::size_t
+                {
+                    if(ec || (reply.size() > 0 && reply.compare(reply.size()-1, 1, "\n") == 0))
+                        return 0;
+                    else
+                        return 1;
+                });
             last_tec += 100ms;
             tick = true;
         }
@@ -243,14 +254,15 @@ int main(int argc, char* argv[])
         ImGui::TableSetupColumn("", 0, 280.0f);
         ImGui::TableSetupColumn("", 0, 1000.0f);
         ImGui::TableNextColumn();
-        ImGui::Checkbox("Update", &update);
-        ImGui::Text("Peak: %.3f", (float)freq_peak);
+        ImGui::Checkbox("Update waterfall", &update);
+        ImGui::Text("Baseband peak: %.3f MHz", (float)freq_peak);
+        ImGui::Text("TEC current: %.6f mA", (float)tec_current);
         ImGui::SliderFloat("Setpoint", &freq_setpoint_local, 0.0f, 40.0f);
         ImGui::SliderFloat("TEC bias", &tec_bias_local, 0.0f, 0.5f);
-        ImGui::SliderFloat("TEC P", &tec_p_local, -0.05f, 0.05f);
+        ImGui::SliderFloat("TEC P", &tec_p_local, -1.0f, 1.0f);
         freq_setpoint = freq_setpoint_local;
         tec_bias = tec_bias_local;
-        tec_p = tec_p_local;
+        tec_p = 0.05f*tec_p_local;
         if(ImGui::Button("Exit"))
             exit = true;
         ImGui::Text("FPS: %d", (int)fps);