SRM-5A
SRM-5A
RetiredShort Haul Modem
Pricing
- Model:
- SRM-5A
- Item Number:
- 10694
- Warranty:
- 1 year
- Compliance:
- price for each modem; 2 required
Overview
The SRM-5A, manufacted 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.
Technical Description
Campbell Scientific recommends connecting the SRM-5A to the data logger'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 data logger'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) |
Power Requirements
- At Computer: uses low power from the EIA RS-232-C/CCITT V.24 data and control signals
- At Data logger: 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
Benefits
- Provides the easiest link for communicating with one data logger over longer distances
- Low voltage transmission levels minimize crosstalk between adjacent lines within the same cable.
- Data are transmitted and received at a balanced impedance, providing excellent immunity to circuit noise.
- Transmits up to 6.2 miles using 19 gauge cable at 9600 bps
- Transmits up to 7.6 miles at 1200 bps
Specifications
- Data Rates
- Up to 9,600 bps
- Transmission Mode
- Asynchronous, full duplex, 4-wire operation
- Transmission Distance or Area
- Up to 12.2 km
(7.6 mi) depending on data rate and wire gage
- 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
- Operating Temperature Range
- 0° to 60°C
(Manufacturer's temperature specification is listed. Limited tests conducted by Campbell Scientific have shown the SRM-5A to perform at temperatures over -25° to +50°C.)
- Current Drain at 12 Vdc
- 2.2 mA
(quiescent)
- Current Drain at 12 Vdc
- 10 to 15 mA
(active)
- Altitude
- Up to 3,000 m
(10,000 ft)
- Humidity
- Up to 95%
(non-condensing)
- Service Requirements
- Dedicated two-twisted pair cable connects one field station with base.
- Dimensions
- 5.2 x 5.2 x 1.8 cm
(2.1 x 2.1 x. 0.7 in.)
- Weight
- 38 g
(1.3 oz)
Accessories
(9)15770
SC932A Interface with Adapter and Mounting Hardware
Retired15751
RS-232 Data Cable Adapter, DB9 Socket (Female) to DB25 Pin (Male)
Limited availabilitySC932A
RS-232 DCE Interface, CS I/O to 9-Pin
Orderable6282
SRM-5A and SC932A Mounting Kit
OrderableCABLE2TP
22 AWG, 2-Twisted Pair Cable with Drain
Orderable6361
Surge Protector Kit for 4-Wire Modem with Mounting Hardware
Retired5563
Surge Protector Kit for 4-Wire Modem with Ground Foot
Retired6536
4-Wire Surge Protector Base Kit
Orderable8125
Flat-Bladed Screwdriver, 2.5 mm Blade x 50 mm Shaft
Orderable
