Protocols

Zmodem  The most efficient file transfer protocol. It provides faster file transfers, auto-download capabilities, batch file transfers, and protection for 16-bit and 32-bit Cyclical Redundancy Check (CRC). It also allows both the sender and the receiver to initiate file transfers. Additionally, it provides security between program applications while eliminating file-transfer errors.

Xmodem  This file transfer protocol includes Xmodem-1K. File transfers with Xmodem require that each byte sent must remain unchanged and that the transfer must occur on a clear 8-bit channel. Data is transferred in 128-byte or 1024-byte (1K) packet sizes. Each packet is assigned a packet number and sent one at a time. Because packet sizes have fixed lengths, a file using padded bytes is rounded up to the next packet. For error detection, sent packets include Checksum or CRC bytes. Packets are sent in sequence, allowing the receiver to verify if a packet was sent or if it is out of order.

Ymodem  This file transfer protocol supports batch file transfers and can send the file name and file size before the actual file data.

Kermit  The least efficient file transfer protocol. Use it when the receiver does not support X/Y/Zmodem software. Kermit sends batch files with the name and time stamp of each file in small packet sizes. The packets contain fields that mark their beginning, length, type, and sequence number.