# X.21/V.35 Module Combination

> Line module label | X.21/V.35
> I/O module label | X.21/V.35 I/O
> Number of I/O ports | 16
> Software release | First supported: 2.10.1, 3.3.2 Final supported: 7.3.x
> Description | 60 W X.21/V.35 synchronous serial interface
> Type | Non-ASIC
> Capability | HDLC framing
> Software features | See ERX Module Guide, Appendix A, Module Protocol Support for information about the layer 2 and layer 3 protocols and applications that this module combination supports.
> Model compatibility | ERX7xx models ERX1410 router
> SRP module compatibility | SRP-5G SRP-5G+ SRP-10G
> Module redundancy support | Not applicable
> Cables and connectors | 200-pin proprietary socket on I/O module DB15 X.21 or DB34 V.35 at remote end Serial signals can travel a limited distance without significant degradation. Slower serial signals can travel farther without degradation than faster serial signals. See “Cable Lengths” row for the maximum cable lengths you can use to prevent signal degradation at various transmission speeds.
> Cable Lengths |
> Transmission Speed (Hz) 2400 4800 9600 19200 38400 56000 2048000 | Cable Length (Meters/Feet) 1250/4100 625/2050 312/1025 156/513 78/256 31/102 8/25
> LEDs | See ERX Module Guide, Appendix B, Module LEDs.
> Alarms, errors, and events | See Monitoring Interfaces in the Configuring X.21/V.35 Interfaces chapter of the JunosE Physical Layer Configuration Guide for Release 8.0.x and earlier.