Extended Addressing 9-3

When the system is initially powered up, the A2400’s are set to the Close Channel condition. This means that no data received by the radio modems will pass to the RS-485 bus at either site. In order to communicate to the modules, one of the A2400’s must be set to the Open Channel condition:

Command: {01OC

Response: *

This command orders the A2400 address ‘01’ to open the ‘data gate’ between the radio modem and the two-module string on the RS-485 bus. Now the host computer may communicate to the modules in a normal fashion:

Command:

$1RD

 

Response:

*+00100.00

(typical)

Command:

$2RD

 

Response:

*+00123.45

(typical)

Note that A2400 address ‘02’ is still in a Close Channel state. No data received by this A2400 will be allowed to pass to the RS-485 bus. Therefore there is no conflict between the two module strings containing identical addresses. Only one A2400 is allowed to be in an Open Channel state at any time.

To access the module string located at A2400 address ‘02’, first close the channel at A2400 #01:

Command: {01CC

Response: *

Now open the ‘data gate’ at A2400 #02:

Command: {02OC

Response: *

Any commands from the host are now directed through A2400 #02:

Command: $1RD

Response: *+00000.00

Command: $2RD

Response: *00005.00

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Omega A2400 manual Command 01OC Response, Command $1RD Response +00100.00 Typical $2RD +00123.45, Command 01CC Response