diff --git a/sdm_modbus/__init__.py b/sdm_modbus/__init__.py
index ecc243f..c323052 100644
--- a/sdm_modbus/__init__.py
+++ b/sdm_modbus/__init__.py
@@ -207,7 +207,7 @@ def _read_all(self, values, rtype):
         return results
 
     def _write(self, value, data):
-        address, length, rtype, dtype, vtype, label, fmt, batch = v
+        address, length, rtype, dtype, vtype, label, fmt, batch = value
 
         try:
             if rtype == registerType.HOLDING: