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REMOTE CONTROL INTERFACING
RCU100 / RCU200 Redundancy control system unit may be monitored and controlled remotely either via a
RS485 multidrop bus or RS232. The connection is made via the 15 way D type on the rear of the RCU
Redundancy control unit and configured as described earlier. If the Redundancy control unit has the Ethernet
option fitted then the unit can also be controlled via its inbuilt web page, TCP and SNMP these are described in
the next section.
The unit transmits and receives data serially in an asynchronous format using the standard ASCII character set.
The serial data consists of message frames composed of the following message characters: STX, BYTE
COUNT, DEVICE ADDRESS, INSTRUCTION, BODY, CHECKSUM, ETX. All characters are compulsory
except for the message body. The presence of a message body is determined by the message type
(INSTRUCTION). The total number of message characters in a message frame may range from a minimum of 6
to a maximum of 255.
The remote control follows the following protocol: (in byte form)
[STX] start of message character #02.
[B]
char defining how many characters are in the message including the STX & ETX parts.
[A]
Address of unit. Address ranges from ASCI character 32 to 47. (configurable via dip switches - see
earlier
[I]
Instruction number.
The possible instructions are:
STATUS REQUEST
STATUS REPLY
CONFIGURE
ETHERNET
[MESSAGE]
numerous characters from length 0 upwards. If no message present enter a 0.
[CHKSUM]
The checksum is used to verify the accuracy of the message frame. The checksum is defined as the
summation of all the bytes in the message, beginning with the 3rd byte (DEVICE ADDRESS) and
extending through the body of the message, ending with the last byte before the checksum. The total of
the bytes is then ANDed with 255 so that the checksum is truncated to a single byte.
[ETX] End of transmission character #03
All message to and from the unit follow the above protocol with a character format of 8 data bits, one stop bit,
no parity, baud rate 300, 2400, 9600 or 19200. Note that all numeric values are shown as decimal.
Issue 3.15
character 32
character 33
character 34
character 4
RCU100 and RCU200 redundancy control units
Page 10
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