If transmission errors occur, follow this procedure to determine the cause of the problem:
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.
Note: Use only externally-powered short-haul modems with Digi products.