If all modules indica te communications failur e , check communications pl ug on the PSIO
module for proper sea ti ng. Also check the wirin g ( CCN bu s — 1:red, 2:wht, 3:blk; S ens o r
bus — 1:red, 2:blk, 3:clr / wht). If a good connect ion is assured and the condit ion persists,
replace the PSI O module.
If only one 8-input module or SMM indicates communication failure, check the communica-
tions plug on that module. I f a good conne ction is assu red and the cond ition persists,
replace the mo dule.
All system operating intelligence rests in the PSIO mo dule. Some safety shutdown logic
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. Out-
puts are controlled by the PSIO and SMM as well.
3. Power is supplied to mo dul es within the control panel via 21-vac power sour c es .
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 transf ormer located within the
starter.
Within the power pane l, T1 supplies power to the LID , the PSIO, and the 5-vac pow er 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 sup ply i ng power to two modules; if additional
modules are added, ano ther power supply will be r eq uired.
Power is connected t o Te r m ina ls 1 and 2 of the power input c onn ection on each module.