wiring

Hex	80	40	20	10	08	04	02	01	Strobe DB-25 > PTS	7442 DB-25 > Pin	CD4515 DB-25 > Pin
DB-25 Pin #	9	8	7	6	5	4	3	2		17 > 12	17 > 22
100 Mhz 10 Mhz	45	49	44	43	41	40	16	15	17 > 23	16 > 13	16 > 21
1 Mhz 100 Khz	20	19	18	17	27	26	2	1	16 > 24	14 > 14	14 > 3
10 Khz 1 Khz	29	28	4	3	31	30	6	5	14 > 25	1 > 15	1 > 2
100 Hz 10 Hz	33	32	8	7	35	34	10	9	1 > 46
1 Hz 0.1 Hz	37	36	12	11	39	38	14	13	? > 47

1 - It's a VERY good idea to run a ground wire from the chassis of the PTS to the chassis of the computer! Remember you are dealing with a parallel interface and you don't need any potential difference between the two chassis when plugging the cable in! Do NOT rely on the ground wire in the AC power cable for this!

2 - PTS pin 42 MUST be connected to ground (pin 50) to enable remote programming!

4 - The PTS parallel interface uses NEGATIVE true logic. This means your data MUST be inverted before you shove it out the printer port!

5 - The inverted data is sent to the printer port. The corresponding strobe signal is then taken low then high to latch the data in the PTS. After the strobe goes high the data can be changed to the next two digits.

6 - There are MANY parallel connections to the DB-25! For instance, Pin 9 (MSB data bit 80) is connected to PTS pins 45,20,29,33 and 37. You will end up with a MUCH smaller cable if you only connect ONE wire to each pin on the computer end and connect this to multiple pins on the PTS end of the cable.

7 - The above chart is one strobe signal short! You can NOT program the 1.0 and 0.1 Hz digits (assuming your PTS has the 0.1 Hz option!) on some PTS units, like the PTS-500. This is because some units require programming of the 100 Mhz digit.

The PTS-160 is unique in that there is NO 100 Mhz digit! The 10 Mhz digit is programmed in binary and allows digits 0 through F (0 to 15 decimal). So 150 Mhz is programmed by sending 15 to the 10 Mhz digit! I took the four leads that normally feed the 100 Mhz digit and wired them instead to the 1 Hz digit. This allowed me to output the 10 Mhz digit on the high order 4 bits and the 1 Hz digit on the low order 4 bits and use ONE strobe signal to enter the data into the PTS.

A couple of options to get more strobe control lines are installing a second printer port or using a 4 line to 16 line decoder. I wanted to keep the other two printer ports open to control other items so I went with the external Decoder. This takes the 4 remaining outputs from the computer and decodes them into 10 or 16 wires depending on which IC is used.

So how does one program all those digits with only 8 data lines? See Program