0FH

		‘A’
		‘0’
LRC Check		‘9’
LRC Check		‘A’
		‘A’
END		CR
END		LF
		LF
RTU mode:
Command message:

	ADR	01H
	CMD1	10H
	Starting data address	05H
	Starting data address	00H
		00H
	Number of data	00H
	(count by word)	02H
	Number of data	04
	(count by byte)
	The first data content	13H
	The first data content	88H
		88H
	The second data content	0FH
	The second data content	A0H
		A0H
	CRC Check Low	‘9’
	CRC Check High	‘A’

Check sum

ASCII mode:

Chapter 4 Parameter SettingsDD Series

Response message:

	ADR	01H
	CMD 1	10H
	Starting data address	05H
	Starting data address	00H
		00H
	Number of data	00H
	(count by word)	02H
	CRC Check Low	41H
	CRC Check Low

	CRC Check High	04H

LRC (Longitudinal Redundancy Check) is calculated by summing up, module 256 and the values of the bytes from ADR1 to last data character then calculating the hexadecimal representation of the 2’s-complement negation of the sum.

For example,

01H+03H+21H+02H+00H+02H=29H, the 2’s-complement negation of 29H is D7H.

RTU mode:

CRC (Cyclical Redundancy Check) is calculated by the following steps:

Step 1: Load a 16-bit register (called CRC register) with FFFFH.

Step 2: Exclusive OR the first 8-bit byte of the command message with the low order byte of the 16-bit CRC register, putting the result in the CRC register.

Step 3: Examine the LSB of CRC register.

Step 4: If the LSB of CRC register is 0, shift the CRC register one bit to the right with MSB zero filling, then repeat step 3. If the LSB of CRC register is 1, shift the CRC register one bit to the right with MSB zero filling, Exclusive OR the CRC register with the polynomial value A001H, then repeat step 3.

Step 5: Repeat step 3 and 4 until eight shifts have been performed. When this is done, a complete 8-bit byte will have been processed.

4-71

VFD-D D specifications

The 3Com VFD-D D is an advanced networking solution designed to meet the demands of modern communication and connectivity. As part of 3Com's extensive portfolio of networking products, this device stands out due to its robust features, innovative technologies, and characteristics that cater to various enterprise environments.

One of the main features of the 3Com VFD-D D is its high-speed data processing capability. Operating at speeds that comfortably support high-bandwidth applications, the device is equipped to handle a multitude of simultaneous connections without compromising performance. This makes it an ideal choice for businesses where consistent, fast access to data is critical.

In terms of connectivity options, the VFD-D D supports a variety of protocols, allowing it to seamlessly integrate with existing infrastructure. Whether through Ethernet, Fiber Channel, or wireless technologies, the device offers versatility in connecting diverse network configurations. This adaptability ensures that organizations can optimize their network setups according to their specific requirements.

The 3Com VFD-D D also boasts advanced security features designed to protect sensitive data from potential threats. With built-in encryption protocols and secure access measures, the device safeguards information while offering administrators full control over user permissions. This heightened security is especially important in today's risk-laden digital landscape, providing peace of mind for organizations entrusting their data to the network.

Moreover, the VFD-D D is designed with scalability in mind. Its modular architecture allows businesses to expand their network capabilities as needed, ensuring that the device can grow alongside their evolving requirements. This flexibility helps organizations manage costs effectively while preparing for future technological advancements.

Another characteristic that sets the 3Com VFD-D D apart is its user-friendly management interface. Administration tasks can be performed quickly and intuitively, reducing the burden on IT staff while enabling efficient network monitoring and troubleshooting. With real-time analytics and reporting capabilities, organizations can gain valuable insights into their network's performance.

Overall, the 3Com VFD-D D combines speed, security, and scalability in a single device, making it a powerful addition to any enterprise network. Its advanced features and technologies are tailored to support the dynamic needs of modern businesses, ensuring reliable performance and robust connectivity in an increasingly interconnected world.

3Com VFD-D D manual 0FH

Models: VFD-D D

END

CMD1

A0H

VFD-D D specifications