
CDN36X User Manual
revision 1.30
Configure DeviceNet Master Scanlist
You must calculate the number of input and output bytes required by your CDN36X
configuration before you can add the gateway to the DeviceNet master scan list. You need to
configure the DeviceNet master to send the specific number of output bytes in its I/O Command
Message, and receive the specific number of input bytes in the gateway’s I/O Response Message.
Once the input and output bytes are mapped in the DeviceNet master, the user application
program will be able to read and write data values to the input and output bytes.
I/O Consume Size
The
I/O Consume Size
is the size (in bytes) of the I/O Command Message data field that is sent
by the DeviceNet master to the CDN36X.
I/O Command data:
[TX Toggle bits 1-8][RX Ack bits 1-8][TX Data Instance 1] … [TX Data Instance 8]
The first byte contains the
Transmit Toggle
bits for all 8
Serial Transmit Object
Instances. The
second byte contains the
Receive Acknowledge
bits for all 8
Serial Receive Object
Instances.
These two bytes are used by the CDN36X and application program to synchronize the transmit
and receive operations. The remaining bytes are the
Transmit Data
attributes for every enabled
Serial Transmit Object
Instance. The number of bytes is determined by the
Data Size
configured
for each enabled Instance. For real and integer numbers, the
Data Size
is predefined by the
selected
Data Type
. For Short_String data type, the
Data Size
attribute is user-defined.
The following equation is used to calculate the CDN36X
I/O Consume Size
. Only include the
Data Size
for enabled
Serial Transmit Object
Instances.
Transmit Toggle
Byte
1
Receive Acknowledge
Byte
1
Serial Transmit Object
Instance 1
Data Size
____
Serial Transmit Object
Instance 2
Data Size
____
Serial Transmit Object
Instance 3
Data Size
____
Serial Transmit Object
Instance 4
Data Size
____
Serial Transmit Object
Instance 5
Data Size
____
Serial Transmit Object
Instance 6
Data Size
____
Serial Transmit Object
Instance 7
Data Size
____
+
Serial Transmit Object
Instance 8
Data Size
____
I/O Consume Size
____
Once you have the gateway configured for your application, you can also read the
Serial Stream
Object’s I/O Consume Size
attribute to find out the required number of input bytes.
MKS Instruments, Inc.
D.I.P. Products Group
40