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Technical Description

The SRM-5A has low voltage transmission levels that minimizes crosstalk between adjacent lines within the same cable. Data are transmitted and received at a balanced impedance, providing excellent immunity to circuit noise.

Campbell Scientific recommends connecting the SRM-5A to the datalogger's CS I/O port via the SC932A interface; a 9-to-25 pin adapter is required. It may be possible to connect the SRM-5A to the datalogger's RS-232 port, but configuration is more complicated; contact Campbell Scientific for more information. Surge protectors on both ends of the transmission line are strongly recommended.


Approximate Range with Various Data Rates and Wire Gage

Wire
Gage		 9600 bps
Data Rate		 1200 bps
Data Rate
19 Gage
(0.9 mm)		 10.0 km
(6.2 miles)		 12.2 km
(7.6 miles)
24 Gage
(0.5 mm)		 4.5 km
(2.8 miles)
 2.8 km
(3.4 miles)
26 Gage
(0.4 mm)		 3.3 km
(2.0 miles)
 4.0 km
(2.5 miles)


Warranty/Repair

Application support and troubleshooting assistance for Campbell Scientific systems equipped with RAD modems are off ered by Campbell Scientific. Repair and warranty service for RAD modems is extended by RAD Data Communications through their distributor, Pacific Data Com. If repair of a RAD modem becomes necessary, please call (213) 494-2121 for a returned merchandise authorization (RMA).

SRM-5A Specifications

  • Data Rates: up to 9,600 bps
  • Transmission Mode: Asynchronous, full duplex, 4-wire operation
  • Transmission Range: up to 12.2 km (7.6 miles) depending on data rate and wire gage; see table at left
  • Line Interface: 5-screw (4-wire and ground) connector block with cable strain relief inside plastic cover
  • Transmission Line: CABLE2TP (for short RS-232 or prewired enclosures) or unconditioned, 4-wire telephone line
  • Transmission Level: 6 dBm
  • Terminal Interface: EIA RS-232-C/CCITT V.24, female integral 25-pin connector
  • Temperaturea: 0° to 60°C
  • Altitude: up to 3000 m (10,000 ft)
  • Humidity: up to 95% non-condensing
  • Length: 5.2 cm (2.1 in.)
  • Width: 5.2 cm (2.1 in.)
  • Height: 1.8 cm (0.7 in.)
  • Weight: 38 g (1.3 oz)

Power Requirements

  • At Computer: uses low power from the EIA RS-232-C/CCITT V.24 data and control signals
  • At Datalogger: combined current drain of the SC932A and RAD modem, which is 2.2 mA quiescent, and 10 to 15 mA active
  • Protection: ac/dc over voltage connected via isolation transformers rated at 1,500 V RMS

a - Manufacturer's temperature specification is listed. Limited tests conducted by Campbell Scientific has shown the SRM-5A to perform at temperatures over -25° to +50°C.

Resources and Links

Ships With

(1) Manual from original mfg--the operation of the RAD modems is discussed in the manual for the SC932A interface; therefore, a Campbell Scientific produced manual entitled "RAD" or SRM-5A" is not available.

Shipping Weights & Dims

Single Box Shipping Weight:
     1.0 lb
     454 g

Single Box Shipping Dimensions:
     6" x 6" x 6"
     15.2 x 15.2 x 15.2 cm