SC932C 9-Pin to RS232-DCE Interface User Guide Issued 27.2.97 Copyright 1997 Campbell Scientific Ltd.
Guarantee This equipment is guaranteed against defects in materials, workmanship, and software. This guarantee applies for twelve months from date of delivery. We will repair or replace products which prove to be defective during the guarantee period provided they are returned to us prepaid.
Contents 1. Installation........................................................................ 1 2. Use with Intelligent Telephone Modems ........................ 1 3. Other Applications........................................................... 2 Appendix A. SC932C to RS232 Device Connection Details ..................................................................A-1 A.1 Cable for Connection to a 25-way DCE Interface ....................................... A-1 A.
SC932C 9-Pin to RS232-DCE Interface The SC932C is used to interface a Campbell Scientific datalogger to modem devices that are configured with an RS232 DCE (Data Communications Equipment) serial port. The most common application is to allow the connection of a RAD-SRM short haul modem or third party telephone modem to a datalogger. The SC932C has the following features: • Generates true RS232 signal levels to the DCE device, resulting in good noise immunity.
SC932C 9-Pin to RS232-DCE Interface Most phone modems can be configured to respond to the DTR line, although this is not always the default setting. Although this feature is sometimes controlled by a hardware configuration switch, more often it is a software setting, e.g. AT&D2&W is the command for a Hayes-compatible modem to force the modem to follow the DTR status. 3. Other Applications The SC932C can be used in more specialist applications.
Appendix A. SC932C to RS232 Device Connection Details This Appendix gives details of the cables required for connection of an SC932C to DCE type RS232 devices, if the SC932C cannot be directly plugged into the 25-way DCE, RS232 socket. A.1 Cable for Connection to a 25-way DCE Interface A standard pin-to-pin cable is suitable. However, if a custom cable is to be made it must make the following minimal connections: 25-Way D Pin No. 2 SC932C 25-Way D Pin No.
Appendix B. Technical Details of Special Modes of Operation The SC932C is designed as a simple plug-in device with no internal jumpers. This Appendix describes alternative modes of operation and also relates these to Campbell Scientific’s original SC932 interface, for those users who are already familiar with that interface. B.1 Power Modes B.1.1 Normal Mode In the normal mode of operation for the SC932C, a continuous supply of 4.
SC932C 9-Pin to RS232-DCE Interface B.2 Handshaking Lines In its normal power mode, and when inactive (i.e. the datalogger ME line is low) the SC932C only holds the RTS line high to provide a source of power to linepowered modems, such as the RAD modem. The DTR line is controlled by the ME line of the datalogger.
Appendix B. Technical Details of Special Modes of Operation the RS232 device will re-awaken the datalogger. This prevents spurious messages from the RS232 device (such as ‘loss of carrier’ messages from a modem) waking up the datalogger. The only consequence of this delay is that specialist software which polls dataloggers at frequent intervals will not be able to wake the same datalogger again during the delay period.
Appendix C. Specifications Data rates: up to 38,400 baud (limited by datalogger) Size: 63 x 55 x 17mm (L x W x D), excluding mating D connectors Operating environment: -25°C to +50°C, 0-95% RH (non-condensing) Connector pin assignments: see Tables C-1 and C-2 Power requirements: sources power from datalogger 5V supply via 9-way interface. Typical current consumption • <100µA with no RS232 load and pin 11 not connected • 2.2mA with RAD-SRM and no communication • 9.
SC932C 9-Pin to RS232-DCE Interface EMC Specification • Emissions BSEN 55022-1: 1995 • Immunity BSEN 50082-1: 1992 Connection Details Table C-1 25-Pin Male Connector Pin-out Pin No. 1 2 3 4 7 11 I/O out in out in Name GND TXD RXD RTS GND PWR 20 out DTR Description Chassis Ground SC932C transmits data on this line SC932C receives data on this line Held active by SC932C Signal Ground If held >3.
