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NSS - NAMSOS


1 29 Nov. 2011: Testing old RS232/422 Converters


1.1 Data transmission


This diagram shows the RS422 signaling used at NSS before October 2011. Note that traffic flows only one way, from the seismometer side, but the RS232/422-converter is optically isolated and draws power from both the RS232 and RS422 side.

NSS data transmission, RS422 system diagram
NSS data transmission, RS422 system diagram prior to October 2011. (Excel drawing)

1.2 Data sheets


Black Box p/n: IC457A-F
Black Box p/n: IC457A-F
Black Box p/n: IC107A-R3
Black Box p/n: IC107A-R3
  • Black Box model no.: IC107AE-R2
    NOTE: Details/data sheet below for model no.: IC107A-R3

1.3 Equipment


  • Black Box "232 <-> 422/485 Converter", model no. IC107AE-R2, S/N: 9912270022 and 0006200180
  • Black Box "RS-232 <-> 422 Converter", model no. IC457A-F, S/N: 97111520372 and 96013498474



2 Test of Black Box "232 <-> 422/485 Converter", model no. IC107AE-R2


2.1 Test of RS422 receiver function


First test is by injecting known good differential RS422 signal into RXA/RXB of Unit Under Test (U.U.T.).

The known good RS422 source has manufacturer P/N: RS001I and vendor P/N: CNV232I485PW+; vendor was Danbit. (This product is discontinued, here's the datasheet.)

Testing Black Box RS232 <-> RS422/485 converter, P/N: IC107AE-R2
Testing Black Box RS232 <-> RS422/485 converter, p/n: IC107AE-R2. Click to enlarge.

Test results
Both UUT are OK.

2.2 Test of RS422 transmitter function


Using oscilloscope to measure voltage levels on TXA/TXB pins.

UUT, S/N ..180, idle mode:

  • TXA: 4.0 V (should be 0 V)
  • TXB: 0.6 V, (should be approx 5 V)
  • TX-LED lit continuously (error)
  • No signal level change when serial characters are sent to RS-232 side.
  • CONCLUSION: RS422 transmit part is defective

UUT, S/N ..022, idle mode:

  • TXA: 1.2 V (should be 0 V)
  • TXB: 5.0 V, (should be approx 5 V)
  • Only signal level change on TXB when sending characters into RS232 side. TXA appears frozen.
  • CONCLUSION: RS422 transmit part is defective

3 Test of Black Box model no.: IC457A-F


3.1 Test of receiver function


Test of receiver (click to enlarge)
Test of receiver function (click to enlarge).

UUT setup:

  • Switch in "DCE" position.

Using known good RS422 transmitter, signals are injected into RXA/RXB-pins of UUT.

  • UUT S/N: ...372
    • Nothing appears on RS232 side
    • CONCLUSION: Defective RX-function
  • UUT S/N: ...474
    • Wrong characters appear on RS232 side in start of sequence of similar characters.
    • CONCLUSION: Defective RX-function

3.2 Test of transmitter function


UUT setup:

  • In order to power the TX-side of RS422 interface, inject RS422 signal on RX-part from known good RS422 source.
Test of transmitter function (click to enlarge).
Test of TX-part. Click to enlarge.

Result:
The transmitter part of both UUT does not seem to work.



4 New RS232/485 converters as of October 2011


New units installed during service vistit to NSS in October 2011:

Black Box p/n: IC620A-F
Black Box p/n: IC620A-F
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Page last modified on November 21, 2016, at 10:56 AM
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