Churchill Nano Link IP67, Technical Manual, Page: 36 / 42

Page 34
9.4.4 Address 252 (S1 = 00111111) – Calibrate Analogues / Test Hardware Outputs /
Reset Counters
Setting this address will carry out an action defined by the state of switch S2. Note that calibration of analogues
requires an accurate current source and an accurate ammeter, and must follow the procedure listed below.
S2
12345678
Reset Counters:
01010101 Reset all counters
Calibrate analogues:
10000001 Record analogue input reading for 20.00mA.
01000001 Record analogue input reading for 2.000mA, calculate correction factors and save in NOVRAM
00100001 Record value needed to give 20.00mA on analogue output 1
00010001 Record value needed to give 2.000mA on analogue output 1, calculate correction factors and
save in NOVRAM
00001001 Record value needed to give 20.00mA on analogue output 2
00000101 Record value needed to give 2.000mA on analogue output 2, calculate correction factors and
save in NOVRAM
10000011 Record RSSI reading for a signal level of +25dBµV
01000011 Record RSSI reading for a signal level of -15dBµV, calculate correction factors and save in
NOVRAM
…THEN…
Test inputs/outputs:
xxxxxx00 Sequence all digital outputs from all off to all on, and all analogue outputs in 20% increments
xxxxxx10 Sequence all digital outputs from all off to all on, and analogue output 2 in 20% increments.
Copy corrected RSSI to analogue output 1. Flash TEST LED in opposite sync to HEARTBEAT
if radio is receiving a valid carrier.
xxxxxx01 Copy digital inputs to digital outputs and uncorrected analogue inputs to analogue outputs.
Flash TEST LED in opposite sync to HEARTBEAT if analogue or RSSI maximum value has
been recorded.
xxxxx011 Copy digital inputs to digital outputs and uncorrected analogue input 2 to analogue output 2.
Copy uncorrected RSSI level to analogue output 1. Flash TEST LED in opposite sync to
HEARTBEAT if analogue or RSSI maximum value has been recorded.
Calibration:
To calibrate analogues, S2 should initially be set to 00000001.
To calibrate analogue inputs, apply a full scale signal (i.e. 20.00mA) to both inputs, then select 10000001 on S2. The
TEST LED should flash in opposite sync to the HEARTBEAT to indicate that the reading has been recorded. Change
S2 back to 00000001. Next, change the input current to 10% of full scale (i.e. 2.000mA), then select state 01000001.
The TEST LED should revert to flashing in sync with the HEARTBEAT to indicate that the calibration has been
completed. Change S2 back to 00000001.
To calibrate analogue output 1, apply a a full scale signal (i.e. 20.00mA) to both inputs, and monitor the current on
analogue output 1. Adjust the input current until the output reads full scale (i.e. 20.00mA), then select state 00100001.
The TEST LED should flash in opposite sync to the HEARTBEAT to indicate that the reading has been recorded.
Change S2 back to 00000001. Next, adjust the input current until the output reads 10% of full scale (i.e. 2.000mA),
then select state 00010001. The TEST LED should revert to flashing in sync with the HEARTBEAT to indicate that the
calibration has been completed. Change S2 back to 00000001.
To calibrate analogue output 2, repeat the above procedure, using test states 00001001 and 00000101.
Calibration of RSSI is not possible without the use of a radio test set, so is normally only carried out in the factory.