Mocomtech CDM-QX operation manual Setup Summary

CDM-Qx Satellite Modem	Revision 5
EDMAC Channel	MN/CDMQx.IOM

Now, a unit that has been designated an EDMAC master not only responds to its own unique bus address, but it will also be configured to listen for the address, which corresponds to its EDMAC Slave. When a complete message packet has been received by the EDMAC Master, it will begin to transmit this packet over the satellite channel, using the overhead bytes, which become available.

Note: The ‘normal’ protocol for the message packet is not used over the satellite path, as it is subject to errors. For this reason, a much more robust protocol is used which incorporates extensive error checking.

At the distant-end, the EDMAC slave, configured for the correct address, receives these bytes, and when a complete packet has been received, it will take the action requested, and then send the appropriate response to the EDMAC Master, using the return overhead path on the satellite link. The EDMAC Master assembles the complete packet, and transmits the response back to the M&C Computer.

Apart from the round-trip satellite delay, the M&C Computer does not see any difference between local and distant-end units - it sends out a packet, addressed to a particular unit, and gets back a response. It can be seen that the EDMAC Master simply acts as forwarding service, in a manner, which is completely transparent.

7.3Setup Summary

To access a distant-end unit:

Designate a Master/Slave pair - Master at the local-end, Slave at the distant-end.

On the local-end unit, enable framing, and EDMAC, defines the unit as MASTER, then enter the bus address. This is constrained to be ‘base 10' meaning that only addresses such as 10, 20, 30, 40 etc, are allowed.

Choose a unique bus address for the distant-end. This should normally be set to the ‘base 10' address + 1. For example, if the MASTER unit is set to 30, choose 31 for the distant-end unit.

On the distant-end unit, enable framing, and EDMAC, defines the unit as SLAVE, then enter the bus address. The orange EDMAC Mode LED should be illuminated.

Set the local-end unit to RS485 remote control, and set the bus address of this local unit. The orange Remote Mode LED should be illuminated.

Once the satellite link has been established, connect the M&C Computer, and begin communications, with both the local and distant end units.

NOTE: EDMAC modes are fully compatible with AUPC modes.

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