SECTION 6. 9-PIN SERIAL INPUT/OUTPUTFIGURE 6.2-1. Hardware Enabled and Synchronously Addressed Peripherals
6.2ENABLING AND ADDRESSING PERIPHERALS

While several peripherals may be connected in parallel to the 9-pin port, the CR10 has only one transmit line (pin 9) and one receive line (pin 4, Table 6.1-1). The CR10 selects a peripheral in one of two ways: 1) A specific pin is dedicated to that peripheral and the peripheral is enabled when the pin goes high; we will call this pin-enabled or simply enabled.

2)The peripheral is addressed; the address is sent on pin 9, each bit being synchronously clocked using pin 7. Pin 6 is set high while addressing.

6.2.1PIN-ENABLED PERIPHERALS

Two pins are dedicated to specific devices, Tape Enable (pin 8) and Modem Enable (pin 5). Pin 6 (Synchronous Device Enable) can either be used as a Print Enable OR it can be used to address Synchronous Devices (Section 6.6).

Tape Enable (TE), pin 8, is raised to enable data transfer to tape. The SC92A Cassette Interface regulates 12 volts from the CR10 to 6V DC to power the RC35 recorder and also provides signal conditioning. ONLY ONE TAPE INTERFACE AND RECORDER MAY BE CONNECTED TO THE CR10.

Modem Enable (ME), pin 5, is raised to enable a modem that has raised the ring line. Modem/terminal peripherals include Campbell Scientific phone modems and computers or terminals using the SC32A RS232 interface.

6-2

The CR10 interprets a ring interrupt (Section

6.3) to come from a modem if the device raises the CR10's Ring line, and holds it high until the CR10 raises the ME line. Only one modem/ terminal may be connected to the CR10.

Print Peripherals are defined as peripherals which have an asynchronous serial communications port used to RECEIVE data transferred by the CR10. In most cases the print peripheral is a printer, but could also be an on-line computer or other device.

Synchronous Device Enable (SDE), pin 6, may be used to enable a print peripheral only when no other addressable peripherals are connected to the 9-pin connector. Use of the SDE line as an enable line maintains CR10 compatibility with printer-type peripherals which require a line to be held high (Data Terminal Ready) in order to receive data.

If output to both a print peripheral and an addressable peripheral is necessary the SDC99 Synchronous Device Interface is required. With the SDC99 the print peripheral functions as an addressable peripheral. If the SDC99 is not used, the print peripheral receives the address and data sent to the addressed peripheral. Synchronous addressing appears as garbage characters on a print peripheral.

6.2.2 ADDRESSED PERIPHERALS

The CR10 distinguishes itself from other Campbell Scientific dataloggers by the ability to address Synchronous Devices (SDs). SDs differ