E1/V.24 Interface Converter

What Kind of Device Is an E1/V.24 Interface Converter?

The TRX E1/V.24 interface converter is a protocol conversion device that converts between a transparent E1 transmission channel and a V.24 (RS232) interface. It is developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd., and is known in the industry as a Raytrans brand product. As an experienced optical multiplexer manufacturer, Raytrans offers this bridge converter to connect data communication equipment with a V.24 interface to optical fiber, microwave, DDN private networks, or other 2M channels, extending the working distance. The device is widely used for remote interconnection of services such as monitoring data, image processing, and video conferencing, and is often integrated into government private network optical fiber communication solutions and military emergency communications vehicle solutions.

Key specifications at a glance: V.24 synchronous 64K/128Kbps · asynchronous 300~115200bps · 4 E1 channels tolerate 8ms delay difference · line bandwidth 7.68Mbps · 75Ω/120Ω E1 interface · power consumption <5W · AC220V/DC-48V power supply

A transparent E1 transmission channel means that a 2M channel is passed through to the opposite end as-is, without protocol rewriting in between; the V.24 interface side connects to the data terminal in synchronous or asynchronous mode. The two ends can be connected over optical fiber, microwave, DDN private networks, or other 2M channels. The working distance of the V.24 device extends along with the coverage of the E1 channel, so there is no need to run long serial cables from the equipment room to the site. In government private network optical fiber communication solutions, this bridge converter can aggregate distributed V.24 data terminals onto the optical fiber backbone network through E1 channels; in military emergency communications vehicle solutions, the Raytrans bridge converter quickly establishes an on-site data extension link thanks to its small size, low power consumption, and DC-48V power supply.


How Is V.24-to-E1 Protocol Conversion Implemented?

V.24-to-E1 protocol conversion works by packing the data received on the V.24 interface into a transparent E1 channel, and the opposite end restores the data into a V.24 signal. The data devices at both ends therefore work as if they were connected to a single long serial cable, and the data content is not modified.

The rate on the V.24 (RS232) side is set in either synchronous or asynchronous mode. The synchronous interface rate supports 64K, 128K, 256K, 512K, 1024K, or 2048Kbps; the asynchronous interface rate is adaptive (300~115200bps); the interface mode can be DTE or DCE; the V.24 interface rate can fully occupy the 2048K bandwidth on the E1 line.

The E1 side complies with ITU-T G.703, G.704, G.823, and other recommendations. The line coding is HDB3, and the interface form is an unbalanced 75Ω BNC interface or a balanced 120Ω RJ-45 interface. The E1 channel supports both CRC-4 and non-CRC-4 verification.

The clock is a key point for interconnecting the two ends. The device provides three selectable clock modes: master clock (DCE), user clock (DTE), and line clock (DCE), and features phase adjustment to compensate for clock differences between the two ends and ensure seamless connection with various devices; the clock source can also be G.703 recovered clock, internal clock, or external clock. If the clock mode does not match the clock source of the opposite-end device, slips or bit errors are likely to occur, so confirm where the opposite-end clock comes from before enabling the service. As an experienced optical multiplexer manufacturer, Raytrans has fully considered the complex multi-device cascading scenarios in government private network optical fiber communication solutions and military emergency communications vehicle solutions in the clock design of the Raytrans series bridge converters.

Core Functions at a Glance

The E1/V.24 interface converter integrates V.24 access, E1 framing, line protection, and self-test functions in a single device. The functions and their descriptions are listed in the table below.

Function	Description
Transparent V.24-to-E1 conversion	Bidirectional conversion between a transparent E1 transmission channel and a V.24 (RS232) interface; V.24 data is transparently transmitted over the E1 channel as-is
Selectable V.24 rate and mode	Synchronous interface rate 64Kbps2048Kbps selectable, asynchronous rate 300115200bps adaptive, interface mode DTE or DCE selectable
Selectable E1 verification	The E1 channel supports CRC-4 and non-CRC-4 verification, matched to the opposite-end frame structure
Automatic E1 detection on reset	Automatically detects the number and delay of E1 channels on reset and automatically selects the available E1
4-channel E1 delay difference tolerance	Allows an 8ms delay difference among 4 E1 channels; DDN private networks with uncertain delay can be networked directly
Automatic line protection	Monitors E1 interface status in real time; both ends automatically cut off lines with LOS or AIS and automatically reconnect when the line recovers
Alarm indication output	Provides alarm output for LOS, AIS, and E1 delay exceeding 8ms; line abnormalities can be collected by external monitoring
E1 line loopback self-test	Features an E1 line loopback function for performance testing and service verification of the E1 channel
Clock mode and phase adjustment	Master clock (DCE), user clock (DTE), and line clock (DCE) selectable; phase adjustment ensures seamless connection with various devices

What Do the Three Differentiated Selling Points Mean on a Private Network Site?

Differentiated Selling Point	What It Means on a Private Network Site
4 E1 channels tolerate an 8ms delay difference; seamless intercommunication with DDN and other private networks with uncertain delay	The 8ms delay difference tolerance means the arrival times of different E1 channels do not need to be aligned one by one; private networks with variable delay such as DDN can also be commissioned in one pass, reducing repeated on-site delay measurement
Automatic cutoff at both ends on line interruption and automatic reconnection on recovery, ensuring private network data is not interrupted	Dual-end automatic protection cuts off abnormal lines when LOS or AIS alarms occur and automatically reconnects when the line recovers, so unattended sites do not need to wait for personnel to arrive on site
Power consumption <5W and DC-48V support, suitable for long-term operation at unattended sites in the field	DC-48V power supply matches the DC power system of communications stations; power consumption <5W places low demands on storage battery capacity, so field sites can operate online for the long term

These selling points make the Raytrans bridge converter from Raytrans perform well in government private network optical fiber communication solutions and withstand the tests of rapid deployment and complex environments in military emergency communications vehicle solutions.

Technical Specifications

Item	Parameter/Specification	Description/Applicable Conditions
V.24 synchronous interface rate	64K, 128K, 256K, 512K, 1024K, 2048Kbps selectable	Configured according to the rate of the opposite-end data device
V.24 asynchronous interface rate	300~115200bps	Adaptive in asynchronous mode
V.24 interface mode	DTE or DCE selectable	Selected according to the master-slave relationship of the interconnected device
E1 interface standard	Complies with ITU-T G.703, G.704, G.823, and other recommendations	International standards followed by the E1 interface
E1 line rate	2048Kbps	The V.24 interface rate can fully occupy the 2048K bandwidth
E1 interface form	Unbalanced 75Ω BNC interface, or balanced 120Ω RJ-45 interface	The two interface forms are selected according to on-site cables
E1 line coding	HDB3	Line coding compliant with G.703 recommendations
E1 verification	CRC-4 or non-CRC-4 selectable	Consistent with the opposite-end E1 frame structure
Clock source	G.703 recovered clock, internal clock, external clock	Selected when interconnecting different transmission devices
Clock mode	Master clock (DCE), user clock (DTE), line clock (DCE) selectable	Features phase adjustment
E1 delay difference tolerance	Allows an 8ms delay difference among 4 E1 channels	Suitable for DDN networks with uncertain delay
Line protection and alarms	Both ends automatically cut off lines with LOS or AIS and automatically reconnect on recovery; outputs alarms for LOS, AIS, and E1 delay exceeding 8ms	Alarms can be output for external monitoring collection
Transmission line bandwidth	Up to 7.68Mbps	Can support high-quality image monitoring systems
Loopback function	Features an E1 line loopback function	Facilitates performance testing of the E1 channel
Dimensions	170mm (L) × 150mm (W) × 37mm (H)	Desktop structure, easy to place on site
Power supply mode	AC220V, or DC-48V selectable	Selected according to site power conditions
Overall power consumption	<5W	Suited to long-term operation at field sites
Operating temperature	–5℃～50℃	Operating ambient temperature range
Storage temperature	–25℃～+55℃	Transportation and storage temperature range
Relative humidity	–25℃～+55℃	Listed as stated in the original product documentation
Operating environment	10%～95%	Normal operation under non-condensing conditions
Atmospheric pressure	70kPa～106kPa	Operating ambient pressure conditions
Installation environment requirements	No corrosive or solvent gases, no dust, no strong magnetic field interference	On-site installation conditions

What Scenarios Is the E1/V.24 Interface Converter Suitable For?

The prerequisite for using the E1/V.24 interface converter is an available E1 (2M) channel on site and a V.24 (RS232) interface on the service-side device. This type of conversion requirement appears relatively often in the following three types of private network scenarios.

Electric Power/Energy Private Networks: V.24 Data at the Substation Side Backhauled over Existing E1 Channels

Electric power private networks already have an E1 transmission system between substations and switching stations and the dispatch center, and V.24-equipped telecontrol, metering, and monitoring data devices operate on site at the same time. The E1/V.24 interface converter packs on-site V.24 data into existing E1 channels and sends it back to the dispatch center, eliminating the need to lay separate lines for data services; when LOS or AIS alarms occur on the line, both ends automatically cut off and automatically reconnect on recovery, keeping the data link on the dispatch side available.

Rail Transit/Expressway Private Networks: Data Channel Extension at Sites Along the Line

Communications equipment rooms, toll stations, and monitoring outfields of rail transit and expressway private networks are usually connected by E1 transmission channels, while the data devices supporting outfield cameras, variable message signs, and sensors are mostly V.24 interfaces. Using the E1/V.24 interface converter to connect V.24 data to the E1 channels along the line extends the data channel from the site to the center together with the existing transmission network; the 8ms delay difference tolerance of the 4 E1 channels allows normal networking even in sections with repeaters and uncertain delay.

Unattended Field Monitoring Stations: Low Power Consumption, DC Power Supply, Online Year-Round

Field monitoring stations and unattended sites have no stable mains power or on-duty personnel; power is mostly drawn from -48V storage battery banks, and cabinet space and heat dissipation conditions are limited. The E1/V.24 interface converter supports DC-48V power supply with overall power consumption <5W, so it can operate online for the long term once connected to the site's DC power supply; when the line is abnormal, both ends automatically cut off and automatically recover. The 170mm×150mm×37mm desktop enclosure can simply be placed in the cabinet, so the site does not need to add a separate rack-mounted device for data conversion.


Selection and Deployment Recommendations

Before selecting an E1/V.24 interface converter, check the following items one by one to minimize on-site rework.

• Is there an E1 (2M) channel on site: both ends of the E1/V.24 interface converter are 2M channels, which can be carried over optical fiber, microwave, DDN private networks, or other 2M channels; if there is only an IP link and no E1 resource, the source of the 2M channel must be resolved first.
• Is the V.24 side synchronous or asynchronous: configure the rate as 64K~2048Kbps for synchronous services; the rate is adaptive for asynchronous services; select DTE or DCE for the interface mode according to the opposite-end device.
• E1 interface form: if the on-site cable is 75Ω coaxial, choose the BNC interface; if it is a 120Ω balanced line, choose the RJ-45 interface, avoiding on-site impedance conversion.
• Opposite-end frame structure and verification: confirm whether the opposite-end E1 uses CRC-4 or non-CRC-4 and keep both ends consistent, otherwise the link cannot be established properly.
• Is the delay certain: when the link passes through networks with unstable delay such as DDN, first network with 4 E1 channels and use the 8ms delay difference tolerance; after reset, the device automatically detects the number and delay of E1 channels and selects the available E1.
• Power supply and installation conditions: choose the DC-48V model when the site has only DC power, and confirm cabinet ventilation, no corrosive or solvent gases, and no strong magnetic field interference.


Conclusion

The E1/V.24 interface converter solves a very specific problem: it allows data devices with V.24 interfaces to continue using the existing 2M channels in private networks such as electric power grids, rail transit, and expressways, extending their working distance. The 8 ms delay difference tolerance of 4xE1 enables direct networking even in private networks with uncertain latency such as DDN; automatic disconnection and reconnection at both ends frees unattended sites from manual intervention; and power consumption <5 W with optional -48 V DC power supply makes long-term online operation at field sites more energy-efficient and easier to power. For electric power and energy private networks, rail transit and expressway private networks, and unattended field monitoring stations, this E1/V.24 interface converter is a low-cost extension channel between existing 2M resources and V.24 data devices.