In addition, two further modules enable cascaded safety-related control systems to be implemented using PNOZsigma relays.
The Pilz PNOZ s11 expansion module is just 45mm wide, yet it has eight normally-open contacts and one normally-closed contact. It can be readily connected to a safety relay from the PNOZsigma range by means of a jumper plug.
Whereas only one PNOZ s11 module can be used with a PNOZsigma relay, the PNOZ s12 expansion unit enables multiple cascading expansion modules to be added to PNOZsigma relays and expansion modules. Just 22.5mm wide, the PNOZ s12 has three normally-open contacts and one normally-closed contact. It also supplies power to any additional expansion modules, which simplifies wiring.
Similar to the PNOZ s12, the new PNOZ s7.1 cascading module has two connectors to enable up to ten modules to be connected, at which point an additional PNOZ s12 can be used so that another ten PNOZ s7.1 modules can be connected. The PNOZ s7.1 is also 22.5mm wide and has four normally-open contacts and one normally-closed contact.
These three new expansion modules offer a cost-effective way to add safety I/O to control systems, as the cost-per-contact is considerably lower than it would be if multiple safety relays were purchased. In addition, wiring is simplified through the use of connecting plugs rather than conventional wires, with the added advantage of a reduced risk of errors being made. This helps to minimise commissioning time and, in the event of a unit having to be replaced, downtime too.