I connect to various Fieldbus devices (all from the same manufacturer and same type as we are an OEM) that I am testing (I have 80 in my test system). I have the dual port PCI Fieldbus card and am running communication manager 3.2 on Windows XP with service pack 2. As part of my pretest (getting the devices on the bus and assigning them a unique address) I connect to a device and change its address to 20 and power off the device to have it drop off the bus then relay in the next device and connect to it and change the address to 21 etc etc---this process makes it easiest for me as then all I have to do is connect to the only device on the bus and know that it is the device I am interested in assigning to it a new unique address as the others are not on the bus. I am able to get 30 devices per port (60 devices total since I have a dual port card). After the 30th device is connected, albeit no devices show up on the bus since they are all powered off, I relay in my 31st device but I can't connect to it on a given port (at this point I have 30 devices that were connected to each port but are now powered off). I have the card configured to operate within the address range of 16-102 for both ports.
What is the limit of the number of devices that can be connected to a given port? What would be the recommended way of connected say 80 devices to a PCI card (40 per port). For my application, after the so called pretest is complete, I do have to have up to 8 devices powered on at the same time (4 per port) so that is why I want to keep the addresses unique per device. By the way I know this is not a physical connection issue with my station as I can connect to all devices when I limit my test to 60 devices (i.e. I can do the first 60 or the last 60 so the wiring etc is good as well as my assigned address space/parameters for the NI card).
Some of My NI card parameters are,
Dlme Link Master Info,
Dlme Scheduling Overhead 4
Def Min Token Deleg Time 84
Def Token Hold Time 700
Target Token Rot Time 4096
Link Maint Tok Hold Time 0x0
Time Distribution Period 5000
Max Inactivity to claim Las Delav 100
Las DB Spdu Distri Period 200
System Management Info,
Primary Time Master 0x10
T1 0x75300
T2 0x2bf200
T3 0x15f900
Clock Sync Interval 10
Dlme Basic Info,
slot time 8
Slpdu Phl Overhead 0
Max Response Delay 10
First Unpolled Node 0x66
Number of Unpolled Node 0x79
This link 0
Min Inter-Pdu Delay 16
Preamble Extension 0
Post Trans Gap Extension 0
Max Inter Chan Signal Skew 0
Time Sync Class 1ms
Thanks
Jim
