Serial Data

The Data field contains the serial message characters (USINT, 8 bit bytes) that will be transferred. The length of this field should at least equal the amount of data specified in Send Length, but can be longer to simplify programming.

All messages sent to the EIP master are kept as coherent as possible, given the constraints of maximum message size. The following rules apply for each data frame sent to the master:

• Preamble and postamble strings are attached to the message per <K141> and <K142> configuration.

• One message is sent for every receive transaction. Even if more than one message will fit into the Receive Length specified, only one message will be sent.

• If the entire message fits within the Receive Length specified, then the whole message will be sent in one transaction.

• If a message is larger than the specified Receive Length, then the message will be fragmented and sent over multiple receive requests. In response to the first request, the beginning of the message is sent. Subsequent responses will send the middle portions of the message, until the end of the message is reached. To assist de-fragmentation of the message, process the Receive Response Flags, and enable pre- and post-amble strings.