Body Control System Description and Operation: Gateway

The instrument panel module (IPM) is the gateway between low speed and high speed GMLAN serial data circuits. The purpose of the gateway is to transfer serial data messages from one subnet to another. The IPM shall unpack the signals from frames received from one bus that are to be transmitted across the gateway and repack the signals into frames to be transmitted on the other bus. The IPM shall be responsible for data passing only. The data passed from one bus to the other shall in no way be modified by the IPM gateway function. The IPM receives 3 distinct types of messages on a given bus:

• Signals the IPM uses for internal functional applications
• Signals the IPM uses for internal functional applications and are passed from one bus to the other bus
• Signals the IPM does not use for internal functional applications but are passed from one bus to the other bus