ICP DAS I-7531-FD Two-channel Isolated CAN FD Signal Repeater User Manual

: June 4, 2024
: ICP DAS

Table of Contents

Introduction
Technical data
Dimension
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ICP DAS I-7531-FD Two-channel Isolated CAN FD Signal Repeater User Manual

Warranty

All products manufactured by ICP DAS are under warranty regarding defective materials for a period of one year from the date of delivery to the original purchaser.

Warning

ICP DAS assumes no liability for damages resulting from the use of this product. ICP DAS reserves the right to change this manual at any time without notice. The information furnished by ICP DAS is believed to be accurate and reliable. However, no responsibility is assumed by ICP DAS for its use, or for any infringements of patents or other rights of third parties resulting from its use.

Copyright
Copyright 2021 by ICP DAS. All rights are reserved.

Trademark
The names used for identification only may be registered trademarks of their respective companies.

Introduction

The I-7531-FD is a CAN/CAN FD signal repeater, which can connect two or more CAN networks with the same baud rate. Based on the signal repeat function of I-7531-FD, users can use different numbers of I-7531-FD to combine tree-shaped and star-shaped CAN network topology, and when there are too many devices on the CAN network, using I-7531-FD can increase the driving force of the CAN signal to drive more CAN devices. In addition, the CAN side of the I-7531-FD has a digital isolation of 2500 Vrms, and the CAN side and the power side also provide 3000 V DC-DC isolation protection, which can effectively isolate the noise interference between CAN networks ,and achieve protection the purpose of a specific CAN network.
Figure1. Application

Features

Supported CAN specification 2.0A/B and CAN FD
Fully compatible with the ISO 11898-2 standard
Detected CAN bus baud rate automatically, maximum support 8000 kbps

Specifications

CAN

Ports| 2
Baud Rate| CAN bus: 5 k ~ 800 kbps
CAN FD: Arbitration rate up to 1000 kbps, data rate up to 8000 kbps
(Note) The data rates are verified by tests, but user-defined baud rates are possible, so the maximum data rate will depend on the concrete operating conditions (cable length, remote stations, etc.).
Isolation| 2500 Vrms for digital isolation, and 3000 V for DC-DC
Terminal Resistor| Build in 120 Ω terminal resistor and support jumper to select
Specification| ISO-11898-2, CAN 2.0A/B and CAN FD
(CAN FD support ISO and Non-ISO standards)
Time Delay| Typ. 175ns (corresponds to ~35m CAN bus length)
Power
Input Range| +10 VDC ~ +30 VDC
Consumption| 1 W
Mechanical
Casing| Plastic
Mechanical
Dimensions (mm)| 72 x 118 x 33 (W x L x H)
Installation| DIN-Rail
Environmental
Operating Temperature| -25 ~ +75 °C
Storage Temperature| -30 ~ +80 °C
Humidity| 10 ~ 90% RH, Non-condensing

Technical data

Block Diagram

Figure 2 is a block diagram illustrating the functions of the I-7531-FD module. Power supply are with 3000 VDC galvanic isolated between each CAN port. Futhermore, there is digital-isolation 2500 Vrms between two CAN ports.
Figure2. Block Diagram

Appearance

Figure3. Apperance

Pin Assignment

Table1. Pin Description

Pin	Name	Description
1	CAN_L	CAN_Low. Signal Line of CAN port 1.
3	CAN_H	CAN_High. Signal Line of CAN port 1.
5	GND	CAN_Ground (or CAN_GND), voltage level of ground of CAN_L and CAN_H in

Note 1:
In normal situation, the CAN_GND does not need to be wired, but the CAN_GND’s voltage level of different CAN devices are not equal in some case. When in this situation, it maybe cause some problems and reduce the stability of the CAN bus system. The user can connect CAN_GND of these CAN devices to let the voltage level be same and eliminate this situation.

Note 2:
Electronic circuits are susceptible to electrostatic discharge (ESD) and will get worse when encountering continental climates, so F.G. provides a path for ESD to lead to the earth ground, thereby enhancing the module’s ability to protect against static electricity. If the user wants to use F.G., both pin 7 and pin 14 need to be connected to the earth ground, because the two pins are not connected inside the module.

Wire Connection

Figure 5. Wire Connection

Status LED

LED	Color	Status	Description

Note:
RUN LED’s twinkling rate correlates with baud rate of CAN bus.
User may see no twinkling when the twinkling period is too short because of the higher baud rate of CAN bus. Besides, the LED could look like always on when bus loading is heavy.

Terminator Resistor Setting

According to the ISO 11898-2 specifications, the bus line of CAN_H and CAN_L must be terminated by resistor for proper operation. The equivalent resistance between CAN_H and CAN_L should be 60Ω. There are some examples below.

Figure6. Terminator Resistor

On the other hand, the I-7531-FD module has built-in two 120Ω terminating resistors, and the user can use the jumper to select whether to enable it. Among them, JP1 is used to adjust the terminal resistance of CAN port 1, and JP2 is used to adjust the terminal resistance of CAN port 2. If the user wants to adjust the terminal resistance, who needs to open the casing of I-7531-FD, and will see the positions of JP1 and JP2 as shown in the figure below:

Figure7. JP1 and JP2 positions

The following connection statuses present the condition if the terminal resistor is enabled (default) or disabled.

Figure8. Adjustment of Terminator Resistor

Baud rate and wire length of CAN bus

The CAN bus is a balanced (differential) 2-wire interface running over either a Shielded Twisted Pair (STP), Un-shielded Twisted Pair (UTP), or Ribbon cable. However, the baud rate of communication is inversely proportional to the wire length. When the baud rate is lower, the ideal CAN bus wire length that can be used is longer, as shown in the following table.
(Note: The ideal CAN bus wire length means the sum of the wire lengths of each CAN bus in a single CAN network.)

Table2. Baud rate and ideal CAN bus wire lehgth

Baud rate [bit/sec]	Ideal CAN bus wire length [meters]
800K	50
500K	100
250K	250
125K	500
50K	1000
20K	2500
10K	5000

In addition, the I-7531-FD can isolate and re-amplify the CAN bus signal, so the user will think that connecting multiple I-7531-FDs in series on the same CAN bus, the CAN bus signal will always re-amplify and then extend the wire length of CAN bus, but the CAN bus signal passing through the I7531 FD will reduce the ideal CAN wire length due to the time delay at the physical layer in fact.
In other words, when the user add one I-7531-FD to the CAN bus, the CAN signal passing through the I-7531-FD will be delayed by 175ns, and the ideal CAN bus wire length will be reduced by 35 meters.
For example, the baud rate used by the user is 500Kbps, and the ideal CAN bus wire length is 100 meters, when one I-7531-FD is connected in series to the CAN bus, the ideal CAN bus wire length will be reduced by 35 meters that is reduced from 100 meters to 65 meters (100 – 35 x 1 = 65).
By analogy, if two I-7531-FDs are connected in series on the CAN bus, it will reduced by 35 x 2 = 70 meters as shown in the below figure.

Figure9. Differences after adding I-7531-FD

Therefore, the baud rate and the maximum number of I-7531-FD supported by a single CAN bus are shown in the following table.

Table3. The number of I-7531-FD supported by a single CAN bus

Baud rate [bit/sec]| The number of I-7531-FD supported by a single CAN bus
---|---
800K| 1
500K| 2
250K| 7
125K| 14
50K| 28
20K| 71
10K| 142