B&B Electronics ZZ24D-NA(NB,NC,ND)-SR - Manual - Manual (Page 65)

Expected Latency
Manual Documentation Number: pn7515_ZlinxIO-0712m 59
6 6 . . E E x x p p e e c c t t e e d d L L a a t t e e n n c c y y
Before you lift a finger towards the perfect wireless installation, think about the impact of wireless communications on your
application. Acceptable bit error rates are many orders of magnitude higher than wired communications. Most radios quietly
handle error detection and retries for you - at the expense of throughput and variable latencies.
Software must be well designed and communication protocols must be tolerant of variable latencies. Not every protocol can
tolerate simply replacing wires with radios. Protocols sensitive to inter-byte delays may require special attention or specific
protocol support from the radio. Do your homework up front to confirm that your software won’t choke, that the intended radio
is friendly towards your protocol, and that your application software can handle it as well.
Assumptions:
 No RF retries.
 Units were less than 3 feet apart during the testing in a clean RF environment.
6.1 Modbus Mode
Modbus with 6 Expansion Modules
Reading Inputs Setting Outputs
SR Base MR Base LR Base SR Base MR Base LR Base
40mS 623mS 105mS 16mS 66mS 18mS
Modbus with no Expansion Modules
Reading Inputs Setting Outputs
SR Base MR Base LR Base SR Base MR Base LR Base
15mS 365mS 104mS 8mS 56.2mS 9mS
NOTE: Add 45mS per analog Expansion Module and 25mS per digital Expansion Module. ZZ8D-Nx-LR radios have a 10% duty cycle max
and were not included in the Latency testing.