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FS-8700-49_Data_Aire_DAP Page 34 of 48
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web:www.FieldServer.com
Tel: (408) 262-2299 Fax: (408) 262-2269 Toll_Free: 888-509-1970 email: support@FieldServer.com
Appendix C.8. Stuck Unit.
Communications on the DAP units requires the operation of a mechanical relay. This can
get stuck. The Front Panel menu of each DAP unit allows a user to execute a diagnostic
test of the comms board. The customer should execute this test and use the Data Aire
installation guide to resolve any issues. Typically a failed unit requires replacement. A
single failed card will fail the whole network. The FieldServer sends polls on the primary
port and expects responses on the secondary port. The fact that we get back a copy of the
poll message on the secondary port does not mean that the units are operating correctly
since this is possible when the units are stuck in pass thru mode.
Appendix C.9. Number of Units
Up to 250 DAP devices can be connected to a FieldServer using the DAP driver.
Normal RS485 network considerations apply - these limit the number of units based on the
load of each node.
• For unit loads only 32 devices per network can be used.
• For .25 unit loads 128 devices can be used on one network segment. If more than 32
full unit loads are required then the network must be segmented and connected via a
repeater
• It may be necessary to use a repeater if total RS-485 length exceeds 1000ft.
It is recommended that tests are performed with a single or few units.