Manual 37278B GCP-30 Series - Genset Control
Page 158/174 © Woodward
Framework Conditions To The CAN Bus
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Transmission Telegram
The data of the following table can be handled by a Gateway GW 4 or a PLC and can be transferred to other
busses. A GCP is sending the data via circular CAN messages.
The transmitting rate of this communication is 125 kBaud.
The CAN ID, on which the GCP is sending is calculated as follows:
CAN ID = 800 + item/generator number (or 320 + item/generator number)
(The item number, Parameter 4, is adjustable and influences directly the CAN ID on which the item sends the vi-
sualization m
essage).
A visualization message which is send out of a GCP has 8 Bytes and is built as follows:
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7
H‘DD MUX num-
ber
data word 1
High-Byte
data word 1
Low Byte
data word 2
High-Byte
data word 2
Low Byte
data word 3
High-Byte
data word 3
Low Byte
In a visualization message the byte 0 is always used to show the hexadecimal value DD. This one defines the
message as a visualization message. As the complete transmission telegram of the GCP includes more than three
words byte 1 sends additionally a MUX number starting with 0. Therefore it is theoretically possible to send
(256 × 3 = 768) words via the CAN ID. The whole telegram is built up as follows:
Line 1: MUX number 0, word 1
Line 2: MUX number 0, word 2
Line 3: MUX number 0, word 3
Line 4: MUX number 1, word 1
Line 5: MUX number 1, word 2
Line 6: MUX number 1, word 3
.
.
Line (n): MUX number (n-1/3), word 1
Line (n+1): MUX number (n-1/2), word 2
Line (n+2): MUX number (n-1/1), word 3
n depends on the total length of the item special telegram and cannot be larger than H’FF.
Coding Of The Current Direction
The current direction can be recognized via the code word prefix. A positive transmitted value indicates power
export (power output, supply) and a negative transmitted value indicates power import (power input, consump-
tion).
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