Oops fix OR on RS485 settings (1c5d969)

src/modbus-rtu.c

@@ -916,7 +916,7 @@ int modbus_rtu_set_serial_mode(modbus_t *ctx, int mode)
                 return -1;
             }
             // Set
-            rs485conf.flags = SER_RS485_ENABLED;
+            rs485conf.flags |= SER_RS485_ENABLED;
             if (ioctl(ctx->s, TIOCSRS485, &rs485conf) < 0) {
                 return -1;
             }