From the version of 15.6, IR829 could support serial interfaces. Please make sure to upgrade your IR829 to version of formal version of 15.5.3M0a (Not authorized to view the specified document 64021) first before upgrading it to 15.6 (Cisco Systems CCO). (The early version of 15.5.2 or others could NOT be upgraded to 15.6 directly or there is some issue. )
IR829 is using RJ45 interface for its serial ports. Please make sure to use the RJ45-to-DB9 serial cable following the EIA-561 standard. The Cisco RJ45-to-DB9 Serial Console Cable (blue cable) does NOT follow the EIA-561 standard, and is not compatible with CGR1240 and IR829 RJ45 serial ports. For details of serial interface pinouts, please refer to https://www.cisco.com/c/en/us/td/docs/routers/access/800/829/hardware/install/guide/829hwinst/pview.html#85723. You may make the adapter by your own with the guide of https://www.usconverters.com/downloads/support/db9_rj45_assembeling_guide.pdf
For the configuration, it is quite similar with CGR1000 (Not authorized to view the specified document 53948). The main difference is the interface name. You need to revise them accordingly. And you may remove “Async mode dedicated” as it is for SLIP only. Here are the main configuration information for IR829. For the baud-rate, you may set it to 9600 for example as well. And then you may access the serial interfaces of "/dev/ttyS1" and "/dev/ttyS2" in GOS. Here below is the example for RS232.
interface Async0
no ip address
encapsulation relay-line
!
interface Async1
no ip address
encapsulation relay-line
line 1
transport preferred none
transport input all
stopbits 1
speed 115200
line 2
transport preferred none
transport input all
stopbits 1
speed 115200
relay line 1 1/5
relay line 2 1/6
For RS485, you need to set the media-type as rs485 for the SERIAL 0. Please notify, the SERIAL 0 supports RS-232 and RS-485 (DCE), and SERIAL 1 supports RS-232 (DTE) only.
interface Async0
no ip address
encapsulation relay-line
half-duplex
media-type rs485
FOR THE LATEST INFORMATION AND A PYTHON SERIAL EXAMPLE, PLEASE REFER TO https://developer.cisco.com/docs/iox/#python-serial-example.