Allen-Bradley 1779-KFMR User Manual page 150

The destination station does not send a reply to this command. Therefore,
this command uses less network time than the write bit with reply
command. However, with no reply, you have no assurance that the
command is actually executed at the destination station.
Write Block with Reply
Use this command to write a block of data into the data table of the
destination host's memory. The maximum data size is 36 bytes. The total
length of the CMD, ADDR, and DATA fields is limited to 40 bytes
maximum.
Command Format:
In the reply, the STS field indicates a successful transaction completion
(00) or an error code.
Reply Format:
Write Block with No Reply
Use this command to write a block of data into the data table of the
destination host's memory. The maximum data size is 36 bytes. The total
length of the CMD, ADDR, and DATA fields is limited to 40 bytes
maximum.
Chapter 9