Lathem DDC2 - Manual (Page 52)

DDC2 / 4-RS -485 Wiring Digital Display Wall Clock Guide Page 46
Appendix C - RS485 Wiring Diagrams
RS485 Data Format
The data string that sends the time to the DDC2 / DDC4 Series Wall Clocks is formatted in such a manner
that a utility can be written to achieve time updates from a personal computer. The following table shows
the layout and explains each character.
Data Format
0#112233445566777Z,CR
The data string is compiled of a total of 16 characters. These characters represent the following.
0
Address byte
# Command for Time update
11 Hex for Seconds (01-59)
22 Hex for Minutes (00-59)
33 Hex for Hour (00-23)
44 Hex for Day of Week (Sunday = 0)
55 Hex for Month (01-12)
66 Hex for Date (01-31)
777 Hex for Year offset from 1984 (000-127)
Z The Checksum (1's compliment of the mod-64 sum of all characters in the string except the CR and
the Checksum)
CR Carriage Return
Transfer of the above string must be done at 9600 Baud, 8 Data Bits, 1 Stop Bit and No Parity.
Requires the SWIFT-485 plus to convert the RS232 signal from the PC to RS485 to send data to the DDC
Series Wall Clocks.
Note: Lathem does not offer a utility to perform this function. This information is supplied so that a 3
rd
party may create such a utility.