Data Line Monitor model RS530LM


A simple to use tool for testing and troubleshooting RS-530 interfaces, the LEDs instantly show the state of all signals.

(Technical note: RS-530 (EIA-530) is a specification for a communications interface that uses a DB-25 connector and V.11 (RS-422) differential equivalents of the main V.24 (RS-232) signals. In addition three link management control signals are implemented using V.10 (RS-423) single ended interfaces, and separate V.11 (RS-422) differential clock lines are used as part of receiving and transmitting data).


  • A complete RS-530 line monitor for speeds up to 10Mb
  • Monitors all thirteen RS-530 signal lines - ten differential and three single ended
  • Six in-line LED monitors show the signals from the DTE - TD, RTS, DTR, TSET [V11/RS-422] and LL, RL [V10/RS-423]
  • Seven in-line LED monitors show the signals from the DCE - RD, CTS, DSR, DCD/RLSD, TSET, RSET [V11/RS-422] and TM [V10/RS-423]
  • Four state monitoring of signals - MARK / SPACE / CLOCKING / NONE
  • Interface or battery powered
  Note: this line monitor replaces the full RS530 breakout box we previously sold, which is no longer manufactured
What's Included

RS530LM data line monitor, two AA size batteries, 0.3 m 25-way interconnection cable, carrying pouch, instruction booklet, 12 months warranty, lifetime support by phone or email

Order code: RS530LM      

*** We regret this item has been made obsolete by the manufacturer and we can no longer supply it ***

Abbreviated Specification & additional information
  • Four state LED monitoring:-
  • (a) Differential (balanced) lines:- red = SPACE/ON (A-B > +0.3V), green = MARK/OFF (A-B < -0.3V), both = data or clock, neither = signal in transition region (-0.3V < A-B > +0.3V)
  • (b) Unbalanced lines:- red = SPACE/ON (> 0.3V above sig. gnd.), green = MARK/OFF (> 0.3V below sig. gnd.), both = data or clock, neither = no signal (< +0.3V relative to signal ground)
  • Speeds: Differential (balanced) up to 10Mb/s, un-balanced up to 500Kb/s
  • Interface connectors: One gold plated female DB25 type connector, one gold plated male DB 25 connector
  • All 25 lines wired through the unit
  • Power: interface power is sufficient for most situations (the power LED indicates the strength of the of the power available), battery powering is possible for extremely weak interfaces. Two AA size batteries (provided) last for over 50 hours
  • Housed in a rigid ABS case
  • Temperature: operating = 0 to + 50 deg.C (32 to 122 deg.F)
  • RoHS compliant, CE marked, made in EU

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                       New Forest Electronics Tel. +44 (0) 1425 650089                 Issue 3.95    28 April 2022