The SRM-5A, manufactured by RAD, is an asynchronous modem used for local communication between a data logger and a computer. Two SRM-5A Short Haul Modems are required: one at the data logger end and one at the computer end. Each short haul modem transmits over an unconditioned 4-wire telephone line or the CABLE2TP two-twisted pair cable. Data rates up to 9,600 bps are possible.