On all new GMSL designs, the HIM pin should be set high to turn high-immunity mode ON. This is especially important in applications that use power over coax (PoC). High-immunity mode enables a different encoding method on the reverse channel to make it more immune to the PoC filter inductors. In order to use high-immunity mode, both serializer and deserializer must have it enabled. Some legacy GMSL devices do not have high-immunity mode. When using a legacy device such as the MAX9271 with a HIM-capable device like the MAX96706, the HIM pin must be set low on the HIM-capable device.