Premier Mounts CDM-600 specifications Setup Summary

CDM-600 Satellite Modem	Revision 7
EDMAC Channel	MN/CDM600.IOM

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.

This approach does not require any additional cabling - connection is made using the normal M&C remote port. Furthermore, the user does not have to worry about configuring the baud rate of the M&C connection to match the lowest data rate modem in the system. The M&C system can have mixed data-rate modems, from 2.4 kbps to 2048 kbps, and still run at speeds in excess of 19,200 baud. It should be pointed out that at 2.4 kbps, the effective throughput of the overhead channel is only 11 async characters/second. For a message of 24 bytes, the time between sending a poll request and receiving a response will be around 5 seconds. (Note that when either of the BPSK Turbo rates is in use, the overhead rate is reduced by a factor of three, and therefore the response time will be around 15 seconds.)

11.3Setup 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, define 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, define 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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