Cables
RS232
:
Via shielded twisted pair.
Connection
:
Signal Digital
Connector #
9Pin ‘D’
Connector #
TX 3
2
RX 4
3
GND 5
5
RS485
: Via a shielded twisted pair.
Connection
: Refer to Section 11.0
Communications
Programmers writing software should refer to the command list below. The communications is a simple
request/reply system. The host computer sends a request and the MCT 300 sends a reply. Hence there
are no special protocols or handshaking involved and it is also quite easy for a person to communicate
with the MCT 300 via a simple terminal.
The timing of the replies it deliberately locked to the wheel revolutions and hence the maximum
communications rate is approx. 18 requests/replies per second. Should the wheel or motor fail then a
timing software system of 10 loops per second takes over so communications is not lost.
When using RS485 a leading “$” or “#” followed by a single, alphanumeric “ID” character wakes up the
target unit and it responds with a reply. Each unit on the RS485 daisy chain has a unique ID and hence
all units may be accessed across a simple single twisted pair cable. Normally ID’s are A-Z, and the
default ID is 1. Hence when adding more MCT 300’s to an existing and running RS485 system, the user
will look for the ID of the unit and assign it a new ID. This process can be repeated for each new unit
added.
The BAUD rate may be changed by a serial command, but this should not be necessary as the filter data
can be extracted at the default 9600 rate and the BAUD rate is not the limiting factor at this
communications speed. Maximum BAUD rate is 57600.
The communications circuits default to RS485 but circuits automatically detects RS232 signals and
when detected the serial stream is automatically routed to the RS232 input and the RS485 goes into a
high impedance state. RS232 style communications will work with or without the ID. This can be useful
as an engineer can walk up to a system, which is on RS485, and plugs in a laptop and immediately starts
a session, man to machine, with the MCT 300. When the RS232 is unplugged the MCT 300
automatically returns to RS485 and the first # or $ will force the ID system to operate again.
Communications Protocol
RAW? RAW?c where c is constituent 0-1. Raw moisture (no SPAN or ZERO)
61
Содержание MCT 300
Страница 9: ...Wall Mount Operator Interface 6...
Страница 11: ...Operator Interface Panel 2X 8...
Страница 38: ...Example of connecting a B B RS485 Converter to the MCT300 OI connector 35...
Страница 41: ...Rear of Sensor 38...
Страница 71: ...Appendix VII Outline Drawings 68...
