Envoy Application Programming Manual

File-System Procedures
Envoy Application Programming Manual—427159-001
C-15
DEFINELIST
For a tributary station, the polling type parameter (Table C-3) specifies how Envoy
should respond when a non-active defined address is selected.
Address-List Format
The address list is usually declared as a string array containing a series of polling
sequences followed by a series of selection sequences. All of the sequences in the array
are the same length and must occupy an even number of byte positions. The specific
format of the poll and select sequences varies somewhat from one protocol to another.
A common poll and select sequence format is:
For example, if the tributary’s controller address is “CC” and its port address on that
controller is “05,” the overall poll or select address of the tributary is:
Byte: 1 2 3 4 5 6
SYN C C 0 5 ENQ
The leading SYN character is used as a pad to force the address to have an even number
of bytes.
Example C-3
on page C-16 is an example of an entire address list:
Table C-2. Polling Type for Supervisor Stations
Polling Type
Parameter Description
0 Envoy should perform continuous poll
1-127 Envoy should poll the specified number of polling cycles
Table C-3. Polling Type for Tributary Stations
Polling Type
Parameter Description
0 Envoy sends RVI
1 Envoy sends WACK
2 Envoy sends NAK
Byte 1:
SYN control character
Bytes 2 and 3:
Controller address
Bytes 4 and 5:
Port address
Byte 6:
ENQ control character