BECKHOFF EL600x/EL602x Serial Port Module Debugging Manual

BECKHOFF EL600x/EL602x Serial Communication Module Debugging, Maintenance, and Troubleshooting Guide

In industrial automation sites, serial communication remains an important way to connect devices such as sensors, barcode scanners, GPS clocks, and frequency converters. The Beckhoff EL600x (RS232) and EL602x (RS422/RS485) series EtherCAT serial port terminal modules are an ideal choice for serial device integration in EtherCAT systems due to their flexible baud rate configuration, 864 byte receive buffer, and optional transmission rate optimization function. However, when faced with practical issues such as setting RS485 bus terminal resistance, switching between half duplex/full duplex modes, TwinCAT process data mapping, and firmware version compatibility, engineers often need a systematic practical guide. This article is based on official technical documentation and presents a comprehensive professional manual covering model identification, installation and wiring, CoE parameterization, process data configuration, firmware updates, and fault diagnosis.

Product Series Overview and Selection Core

The EL600x/EL602x series includes single channel and dual channel versions, covering mainstream serial interface standards:

Model Interface Type Channel Number Key Characteristics

EL6001 RS232C 1 full duplex, RTS/CTS hardware handshake, up to 15m in length

EL6021 RS422/RS485 1 Full/Half Duplex, Differential Signal, Maximum 1000m

EL6021-0021 RS422/RS485 1 Increase bias resistance, suitable for connecting in the middle of the bus

EL6002 RS232C 2 dual channels, each channel with a DE9 male head

EL6022 RS422/RS485 dual channel, DE9 female head, each channel can output 5V/20mA power supply

All models have a default baud rate of 9600, 8 data bits, 1 stop bit, and no checksum (8N1). Key selection decision: If long-distance (>15m) or multi node bus is required, EL602x should be selected; If the site is an RS232 device, select EL600x. EL6021-0021 is designed specifically for multi EL602x parallel scenarios, and its higher bias resistance can avoid bus level abnormalities caused by parallel bias resistance.

Precautions for Mechanical Installation and E-Bus Power Supply

The EL600x/EL602x adopts a standard 12mm or 26mm (dual channel) width housing and is installed on a 35mm DIN rail (compliant with EN60715). Attention should be paid during installation:

No communication module limitation: In the same I/O station, it is not allowed to install more than two "no communication modules" that do not participate in E-Bus data transmission in parallel, otherwise it will affect the reliability of data transmission.

E-Bus current consumption: EL6001 typical 120mA, EL6021 typical 170mA, EL6002 typical 170mA, EL6022 typical 250mA. It is necessary to ensure that the bus coupler (maximum 2A) or E-Bus power module (such as EL9410) can provide sufficient current. TwinCAT System Manager will automatically calculate and prompt for insufficient power supply (display exclamation mark).

Grounding and shielding: The terminal module provides shielding connection points (FE) for eliminating EMC interference. It is strictly prohibited to use functional grounding for releasing residual current or potential difference - the shielding layer is only used for releasing high-frequency interference and cannot replace protective grounding.

Wiring points: RS422/RS485 terminal and bias resistor

The physical layer wiring of RS422/RS485 is the most error prone link in on-site debugging, and its core lies in the reasonable configuration of terminal resistors and bias resistors.

3.1 Terminal Resistance

RS422 (full duplex, point-to-point or multi-point reception): A 120 Ω terminal resistor must be connected across the receiving end (RxD+/RxD -). It is recommended to use a clear linear topology with as short branches as possible.

RS485 (half duplex, multi station bus): The terminal resistor is only placed at the devices at both ends of the bus, and the intermediate node is not connected to the terminal. Each terminal resistance is 120 Ω.

3.2 Bias resistor (unique to EL602x)

When the bus is idle, the differential lines (A/B or T+/T -) need to maintain a certain level to prevent false triggering. EL602x has an integrated bias resistor (pull up to power, pull down to ground). But if multiple EL602x are connected in parallel in the bus, the bias resistance of the parallel connection will be too small, which will increase the bus load and may cause abnormal voltage levels. At this point, EL6021-0021 (with increased bias resistance) should be placed in the middle of the bus as a "relay" node to reduce the overall bias current.

3.3 Definition of Wiring Pins (Single Channel EL6021)

Terminal 1: TxD+(sending positive)

Terminal 5: TxD - (Send Negative)

Terminal 2: RxD+(receive positive)

Terminal 6: RxD - (receive negative)

Terminal 3/7: GND (internal short circuit)

Terminal 4/8: Shielding (internal short circuit)

The dual channel EL6022 uses a DE9 female header, and the pin allocation is detailed in the document (channel 1: Pin2 Tx+, Pin3 Rx+, Pin7 Tx -, Pin8 Rx -); Channel 2 is similar).

3.4 Half Duplex/Full Duplex Mode Settings