![Cincinnati Sub-Zero EZT-570S Скачать руководство пользователя страница 7](http://html.mh-extra.com/html/cincinnati-sub-zero/ezt-570s/ezt-570s_reference-manual_2607293007.webp)
EZT-570S User Communication Reference Manual
7
2.1.1 Interface
Converters
The purpose of an interface converter is to allow two different buses to be connected together.
Interface converters are required when connecting an EIA-232 port to an EIA-485 bus. The EIA-485
bus is a half duplex bus. This means that it can only send or receive data at any given time. Some
interface converters on the market provide the ability to have full duplex with the EIA-485 bus. This is
accomplished by using two receivers and transmitters tied in tandem. This type of converter will not
work with the EZT-570S controller. Be sure that the model you purchase is designed for half duplex.
Another consideration when selecting an interface converter is how the converter handles switching
between transmit and receive. Typically it is accomplished via a handshake line from
the PC. When
data flows into the converter from the PC, a handshake line is placed high. When data flows out of
the converter to the PC, the handshake line is placed low. In this way, the handshake line controls
the direction of information. Another method of achieving this is to use a built-in timer. The converter
switches to transmit when a character is sent to it from the PC. After a period of time when the PC
has not transmitted, the converter switches to a receive mode.
It is important that you understand how your converter accomplishes this task. You are required to
wire this feature or make settings on the converter to enable this function. The PC will not talk to the
controller correctly with out properly setting this. Your converter may also require settings through dip
switches to set up communications parameters like baud rate, data bits, start bits, stop bits and
handshaking. The converter may also require a separate power supply. Some converters get their
power from the handshake lines of the PC. If you rely on this method, you will need to wire these
additional lines. In addition, your software must set these lines high. A more reliable method is to
use the external power supply. This is especially necessary when using a laptop computer. See the
documentation that is provided with your converter for more detail.
Not all converters are equal in performance. If your chamber operates in a harsh, electrically noisy
environment, this can cause less robust converters to work intermittently or not at all. CSZ has only
tested the converters listed below; however, CSZ makes no claims as to the performance or
compatibility of these converters with your PC. These converters are equipped with automatic send
data control circuits, driver control in the converter hardware, so you don’t have to work with software
at all. The circuit monitors data flow and enables the driver during transmission and automatically
disables it when no data is being sent. There is no need to rework software or install new drivers.
B&B Electronics
707 Dayton Road
PO Box 1040
Ottawa, IL 61350
Phone 815-433-5100
http://www.bb-elec.com
Part #
485OI9TB
for EIA-232 to EIA-85
Part #
485PS2
(external power supply – required if handshake lines unavailable for power)
RESmith
4311 Smith Drive
Hamilton, OH 45011
Phone 513-874-4796
http://www.RS485.com
Part #
ASC24T-B9FPS
for EIA-232 to EIA-485 (provided with adapter cables and power supply)