Technical Support

Glossary Of Terms

ATS Tech Support is available to answer your questions at (800) 444-7161
from 8:00am to 5:00pm Central Time.

e-mail us at
fax (318) 797-4864
Please review the following examples to see if the solution to your problem is listed below.

(AP, MC)

Possible Cause
Recommended Fix
My relay output clicks but does not turn on my device hooked to it.
The relay has a "dry contact".
The relay is a switch, you have to supply a voltage to the contacts.
I am ringing a bell with the output and when the time switch matches a program set, the bell rings constantly.
Output is not set to pulse.
You may need to correctly set your pulse duration (See "setting the pulse" in the users manual).
I entered an alternate basic plan but the clock will not implement it.
This plan is programmed but not being used by an annual plan or manually implemented.
For a one day occurrence use menu 31, or implement it with an annual plan.
My AP21 stopped working at the end of February.
Y2K Problem.
Version 1.08 and before had a software problem. Upgrade to latest software, see Application Note AN2000LP for alternate solutions.
My AP21 time drifts on backup power.
Crystal frequency is off.
Adjust the frequency trimmer capacitor until the frequency is 32.768 Khz +/- .003%
Why does my AP21 have 2 fuses?
One is for the 120volt operation and the other for 12 volt.
If you are running on only one voltage, the other fuse can be used for a spare.
Unit won't remember time/sets after a power down.
Possible defective backup capacitor.
Replace. Testpoint 1 has to be shorted to ground to remove voltage anytime parts are replaced on the PCB.


Possible Cause
Recommended Fix
Some of my LEDs are out.
The display ribbon cable could have connection problems.
Reseat or replace the ribbon.
Some of my LEDs are out.
Bad LED(s)
LEDs are usually wired in groups of 5. if one fails all 5 will go out, replace the faulty LED.
My clock flashes "UER 1.2" when I plug it in.
This is the version number of the software in the unit.
The display is waiting to receive serial data from the computer.
My AE device will not recieve serial data from my computer.
Check the connection and the baud rate.
AE devices receive data at 2400 baud. Also on the computer needs DTR, DSR, & CTS shorted together (4,6 & 8) for a DB9 or (20, 6 & 5) for a DB25.
My RS485 device will not send or receive data.
Reversed signal lines or termination problems.
Check proper orientation. RS485 also needs 100 ohm termination resistors at the end of a run.
You spec. your count up timer at 25 hertz but mine will not do that.
Input filtering.
The count comes in on a switch input. These inputs are filtered to stop noise. Remove the capacitor from this input.

Glossary of Terms

A device for converting an analog voltage to a digital count.
A signal that can be continuous between 2 values. (ex. 4 to 20 ma.)
A positive electrode of a device. (LED, diode)
American Wire Gauge. A standard for measuring the diameter of a wire.
The rate at which serial data is transmitted between 2 devices (in bits per second).
A signaling device. It emits sound when a voltage is applied.
A component for storing an electrical charge or reducing voltage fluctuations.
The negative electrode of a device. (LED, diode)
A device that counts input pulses or contact closures.
A signal that is either max or min only. (one or zero)
Refers to devices which display digital time characters and/or numbers, Also called AE or CC display devices; or refers to the actual LCD or group of LEDs in a device.
A device that displays a time duration from a beginning point.
The device housing.
Global Positioning System. 24 satellites that transmit positioning and time information traceable to the NIST atomic clock.
An unwanted fluctuation in the voltage of a circuit (caused by the supply voltage, bad capacitors, and/or electromagnetic noise of other equipment or devices).
I. C. (CHIP)
A semi-conductor component of Integrated Circuits
A Liquid Crystal Display that areas darken when a current is passed through that area
A transparent window that protects the displays.
A Light Emitting Device (semi-conductor) that emits light when a current is passed through it.
To synchronize to the power line. The clock counts the power line transitions and uses this as a time base to keep time.
1/1000 of an ampere. (.001 amps)
A component that uses an opto-electric transmitter and receiver to transfer data without electrical continuity.
A Printed Circuit Board (usually fiber glass) that support the electronic components for a circuit.
A collection of time sets to do a particular function (a Schedule).
The Central Processing Unit of the device. Processes the instructions to perform a particular function.
A momentary output activated for a pre-defined period of time.


An electromechanical component that controls a voltage to a device.
The smallest signal increment that can be detected by a measurement system. Resolution can be expressed in bits, in proportions, or in percent of full scale.
A standard for serial communications between a device and a computer.
A program that skips a single day or group of days during which all events (STEPS) are skipped.
A single event within a program that will perform a function or combination of functions that will act upon the output relay(s).
A component for connecting wiring to a device or PCB.
A temperature sensor created by the joining of two dissimilar metals.
Metal Oxide Varistor is a device whose impedence changes appreciably in response to applied voltage to limit the current to vulnerable components.
A measurement of power equal to Voltage times Amperage.
(1 watt = 120 volts X 0.00833 amps)