Data Sheet

3Serial Tap

Note 3

"TTL" here means "digital signals of microcontrollers, microprocessors, and other

ICs." TTL inputs of the Serial Tap are also compatible with CMOS circuitry. Most

importantly, "TTL" serial signals are usually inverted with respect to RS232 signals: a

LOW (negative voltage) on an RS232 line corresponds to a HIGH level on a serial

TTL (CMOS) line, and HIGH (positive voltage) on an RS232 line corresponds to a

LOW level on a serial TTL (CMOS) line.

Note 4

TX, RX, RTS, CTS, DTR, and DSR lines of the primary DB9 connector located on the

left of the Serial Tap are connected in parallel with RS232 inputs on the terminal

block. This can be seen on the Block Diagram of the Serial Tap.

Note 5

Jumpers and bi-color LEDs on RS232 lines give the Serial Tap the second use as a

simple mating and signal checking tool for serial devices.

Note 6

This statement pertains to the latest revision D of the product. On the earlier (and

now obsolete) revision C, yellow LEDs used to turn on when the lines went HIGH.