Keithley CTM-05A Counter / Timer Board

The Keithley CTM-05A is an ISA-bus counter/timer board for PC-based test systems, delivering precise timing and event measurements across five independent 16-bit counters. Built around the industry-standard 9513 counter/timer chip, it supports frequency, period, pulse width, and event counting up to 7 MHz input rates. The board enables software linking of all five counters to construct 32-, 48-, 64-, or 80-bit counting chains, making it suitable for automated testing, data acquisition, and process control requiring high-resolution timing accuracy.

Technical Specifications Counter Architecture

Five independent 16-bit counters with up/down counting in binary or BCD format

Maximum input rate: 7 MHz

Load and Hold Registers on each counter

Frequency measurement to 7.5 MHz (requires two adjacent counters)

Pulse width measurement: 70 ns minimum (high and low)

Period measurement supported Pulse Output Capabilities

Available on channels 0–4

Minimum pulse width: 2 µs

Minimum pulse period: 4 µs

Maximum pulse period: 2,147 seconds Event Counting

16-bit mode (channels 0–4): maximum 65,535 counts

32-bit mode (channels 0–3): maximum 4,294,901,760 counts Onboard Time Base

Selectable 1 MHz or 5 MHz

Accuracy: ±0.01% over 0–70°C Digital I/O

8-bit input and 8-bit output ports

Counter inputs software-selectable for active-high or active-low

Hardware or software gating per counter

40-pin header for digital I/O connector Electrical Characteristics

Input low: 0.8 V max, 1 mA max current

Input high: 2.2 V min, –10 µA max current

Output low: 0.4 V max at 3.2 mA

Output high: 2.4 V min at –200 µA

Key Features

Software-linked counter chains up to 80 bits

Dual-mode counting (binary or BCD)

TTL-compatible I/O levels

Hardware and software gating control

Compatibility & Integration Standard 37-pin D-type male connector with mating 37-pin D-female (ITT/Canon DC37S equivalent). Optional accessories include CA4037 cable, STC-37 screw terminal connector, STA-U Screw Terminal Board, and STP-37 Screw Terminal Panel (with C1800 cable).