Specifications

10 Chapter 3 EIA-232 asynchronous interface
Data rate vs. cable length recommendations
• The maximum length is the amount of cable that is connected to a
Digi supplied interconnect device, such as Quad or Octa cables and
boxes.
• The maximum length is based on a cable rated at the following:
- 12.3 pF/foot, conductor to conductor
- 22.4 pF/foot conductor to shield
• In situations where low-capacitance cable is unavailable, or very
long cable runs are required, “short-haul” modems can be used to
increase the effective range of the EIA-232 interface. Short-haul
modems are similar to standard modems, except that they are
connected directly to each other via a cable instead of going through
a telephone circuit.
• Use only externally-powered short-haul modems with Digi products.
Resolving transmission errors
If transmission errors occur, follow this procedure to determine the cause of
the problem:
1. Reduce the baud rate.
2. Reduce the cable length.
3. Use a cable with a lower capacitance per foot rating.
Data rate (bps) Maximum cable length
57,600 or less 100 feet
115,200 80 feet
230,400 40 feet
460,800 20 feet
921,600 10 feet