Campbell SC32A, Справочное руководство

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Reference Manual
3
In the following discussion, the term ‘enable’ means the method which activates a
peripheral by setting an assigned datalogger I/O pin high. The term ‘address’
means the method which selects peripherals by addressing.
5.1 SC32A With 21X and CR7 Dataloggers
These dataloggers use the pin-enable method. The SC32A is a modem-type
peripheral, and only one modem may be connected to these dataloggers. With
two modems connected, the magnitude of a logic high is too low for proper
communication.
There are three cases were the SC32A could be used with this category of data-
loggers:
Case 1. An SC32A interfaces a terminal/computer to the datalogger and no
peripherals enabled by pin 6 are connected. In this case, the datalogger is in the
telecommunications mode and all data transfer is a result of pin 5 being enabled.
The jumper has no effect.
Case 2. An SC32A interfaces a datalogger to an RS232 printer-type peripheral.
The jumper must be removed (i.e. left in its default position) so that data is sent to
the peripheral when pin 6 is high. Because only one modem can be connected to a
datalogger, data transfer resulting from telecommunications (pin 5 high) is
impossible in this situation. This means, for example, that a 21X connected to a
printer via the SC32A cannot communicate with a PC.
Case 3. An SC32A interfaces a terminal/computer to the datalogger and at least
one other peripheral enabled by pin 6 is directly connected to the datalogger (e.g.
a Storage Module). The jumper must again be removed. The dataloggers are
designed to delay output to a peripheral enabled by pin 6 while pin 5 is active
(i.e. there is no output to peripherals while in the telecommunications mode).
When telecommunications is exited, pin 5 is set low and output to peripherals
enabled by pin 6 is resumed. If the terminal/computer is left on, and the baud
rate is compatible, data sent to the Storage Module will also appear at the
terminal/computer.
5.2 SC32A With CR10 Datalogger
To understand where the SC32A can be used and the significance of the jumper, a
short discussion of the CR10’s communication methods is necessary.
The CR10 enters telecommunications in two ways:
1. Pin 5 enables telephone modems and the SC32A for telecommunications.
2. To achieve telecommunication through an RF modem or CR10KD Keyboard/
Display, the CR10 addresses the appropriate peripheral using a combination of
the Synchronous Device Enable (SDE, pin 6), Clock/Hand Shake (CLK/HS,
pin 7) and Transmit (TX, pin 9) lines.
Addressable peripherals include the SM192/716, the CSM1, the CR10KD, the
SDC99 Synchronous Device Interface and the RF95 (in SDC state). In addition to
the addressing process, the SDE line also enables peripherals in the same way as
the PE line (pin 6) of the 21X and CR7 dataloggers. Simultaneous use of
addressed peripherals and peripherals enabled by pin 6 (SDE) should be avoided.
When addressing occurs, enable-type peripherals will receive address information
which, at a minimum, will mix garbage in with data, and at worst, cause the
peripheral to lock up and become inoperative.