Communicating with the Carrier and M-MODULES

The defaults that are restored using the above procedure are those set by the manufacturer of the Ethernet device and not by C&H Technologies, Inc. The default settings of the carrier as received from the factory at C&H are different in several key areas. The user must manually return these settings to the default as set by C&H in order for the carrier to operate properly. Refer to APPENDIX C or details on the factory default settings as received from C&H Technologies, Inc.

4.3 COMMUNICATING WITH THE CARRIER AND M-MODULES

The EM405D uses a simple binary command structure to communicate with the host software. The commands allow the user to either write or read registers residing on the EM405D or on each M-module. By writing registers residing on the EM405D, the user can identify the module, perform device configuration, and receive status. The registers residing on each M-module are specific to the particular M-module. Refer to the M-module’s documentation for register details.

Each command consists of a command-id byte, a module number on which the command is to be executed and parameters, if required. The commands are listed in Table I. Details of each command are found throughout the rest of this section.

Table I. Command Summary

Binary
Command-id	Function
0x20	Write Data
0x30	Read Data
0x40	Block Write
0x50	Block Read

4.3.1 Error Handling

Each command will return a status code as the last byte returned. This status code will indicate whether the command completed successfully or whether an error occurred while the EM405D was performing the command. Table II shows a list of potential status codes that may be returned.

Table II. Status Code (SC)

Value	Meaning
0x00	Successful
0x01	Invalid Command
0x02	Invalid Parameter
0x03	Module did not respond*

* Note: Applies to M-module requests only.