If all modules indicate c om m un ications failure, ch ec k c om m un ications plug on the PSI O
module for proper sea ting. Also check the wir ing (CCN bus — 1:red, 2:wht , 3:blk; Sensor bus —
1:red, 2:blk, 3:clr/ wht). If a good connection is as s u red and the condition per s is t s, replace the
PSIO module.
If only one 8-input module or SMM indicates communication failure, check the
communications plu g on t hat module. If a good connec t ion is assured and the condit ion
persists, replace t he m od ule.
All system operating intelligence rests in the PSIO modu le. Some safety shutdo wn lo gic
resides in the SMM in case communications are lost between the 2 modules. The PSIO
monitors conditions using input ports on the PSIO, the SMM, and the 8-input modules. Outputs
are controlled by the PSIO and SMM as well.
3. Power is supplied to mo dul es within the control pane l via 21-vac power sources.
The transformers are located within the power panel, with the exception of the SMM, wh ich
operates from a 24-v ac power source and has i ts own 24-vac transform er located within the
starter.
Within the power pane l, T1 supplies power to the LID , t he P S I O, and the 5-vac power sup-
ply for the transducers. The other 21-vac transformer is T4, which supplies power to b oth 8-
input modules (if prese nt). T4 is capable of supply i ng power to two modules; if additional
modules are added, ano ther power supply will be req uired. Power is connect ed to Termi-
nals 1 and 2 of the power input connection on each modul e.