Issue
How many messages are buffered on a Door Controller 7910A and 7920 DPU?
Product Line
TAC INET
Environment
- I/NET Seven
- Door Controllers: DPU 7910A, DPU 7920, and SCU 1284
Cause
Even though every device in the system contains a message queue, only a few of the devices will successfully buffer the queued messages for later distribution. All controllers and Taps distribute messages out of their RS485 port even with the absence of any LAN communication. This is due to the fact that there is no requirement for an acknowledgment to be received at the generating device. The RS485 LAN is for both solicited and unsolicited message traffic. The only devices that perform extended buffering are the ones that directly communicate to polling devices such as the 7801 Taps, 7803 Taps, 7804 Taps, and all DPUs/SCUs. The MRs, ASCs, and UCs do not generate messages; messages relating to these devices are generated by the relevant MRI, MCI, etc.
Resolution
Refer to the Database Caching in the Door Controller Chapter 9-11 in TCON 300-05/17 for full details.
For the 7910A and 7920 see the following details:
- Controller software before v.2.20 = 100 messages
- Controller software for 2.20 and later = based on the number of resident individuals (see table below).
